Manga: Arpeggio of Blue Steel

The ships of the Fleet of Fog. Front row (left to right): Super Battleship Yamato, I-401 Iona, Heavy Cruiser Takao; Back row (left to right): Fast Battleship Haruna, Fast Battleship Kongou, Fast Battleship Kirishima.

"Dreifach ist der Schritt der Zeit:
Zögernd kommt die Zukunft hergezogen,
Pfeilschnell ist das Jetzt entflogen,
Ewig still steht die Vergangenheit."
Motto of I-401, by Friedrich Schiller in Sprüche des Konfuziusnote 

Arpeggio of Blue Steel (Aoki Hagane no Arpeggio) is a manga by Ark Performance, centering on humanity, having been pushed back from global warming raising the sea level, and their conflict with the Fleet of Fog, archaic-looking WWII-era ships who have been using Game Breaker weapons and armor to ensure that humans can't set keel or pontoon into the world's oceans without risking getting blown to smithereens. The world's navies banded together 17 years before the opening chapters of the manga and were utterly annihilated.

Since then, Japan's fortunes have gone downhill in a huge way: Japan relied on importing and exporting for both raw materials and income for its economy; without either, the nation's industry has fallen quite far. In this rather bleak future is one shining ray of hope: Blue Steel, a bunch of ragtag misfits led by their captain, one Gunzou Chihaya. Having somehow acquired a Fog ship of their own, the Fog submarine I-401, only Chihaya and his crew can actually claim Fleet of Fog kills in battle.

However, the I-401 and her crew have more enemies than just the Fleet of Fog: The Japanese government are very keen on getting their hands on what initially was their ship. Bureaucrats look at I-401 and drool. However, what nobody realized is that I-401, like many ships now in the Fleet of Fog, has a mind of her own, and a body to fit.

The manga has been serialized in Young King OURS magazine since September 2009, and has at least nine volumes compiled so far. Meanwhile a spinoff titled Salty Road, which focuses on Heavy Cruiser Takao during her infiltration of Yokusuka, as well as her interactions with the people living in the city, began serialization on October 2014.

An anime series sublined Ars Nova was aired during the Fall 2013 Anime season. Two movies have since been announced for it, both of which draw major plot points from the manga: the first one, which aired on January 2015, is three parts Recap Movie and one part continuation, and details the events leading to the delivery of the Vibration Warhead to the United States Navy as well as the circumstances that force Gunzou and his companions to flee the Americas... right into the path of Battleship Hiei and her escorts. The second movie, entitled Ars Nova Cadenza, is a straight sequel, and previews have so far revealed the involvement of Musashi and Gunzou's father Shouzo, as well as Supreme Battleship Yamato.

The anime is streaming on Crunchyroll. Viewers living in the following areas may watch it legally there: North America, UK, Ireland, Australia, New Zealand, Netherlands, Scandinavia, South Africa, Central America, South America, Caribbean, Turkey, Italy, Austria, Germany, Lichtenstein, Luxembourg, Switzerland, Belgium, Poland, Denmark, Czech Republic, Hungary, and Romania.

Compare to Kantai Collection, another series (with its own anime adaptation, to boot) that also features female personifications of World War 2 ships. The two franchises have collaborated on an in-game event for December 2013, which features characters from the Ars Nova anime assisting the girls from Kancolle against Kongou and Maya.

In September 2014, during the 2014 Tokyo Game Show, Wargaming.net announced a collaboration project between this series and their latest creation, World Of Warships.note 
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    Tropes shared between media 

  • A.I. Is a Crapshoot: Somewhat inverted: Before getting 'Mental Models', the Fleet of Fog ships were pretty straightforward about their goals and how they went about achieving them. Now that they have them, however, they're finding that alongside having the point of view of humans, they're also starting to pick up quirks like humans too...
  • All There in the Manual: Much about the information about the world setting, as well as the history of the world of Arpeggio (including an actual timeline) prior to the attack of the Fog Fleet en masse can be only found in supplementary material included in the tankoubon compilations of the manga. Among these include Humanity's first encounter with the Fog Fleet (through Bismarck) during the First World War, as well as hints as to why the Fog ships themselves seem to only have half of the instructions given by the Admiralty Code (the answer: because it was not reactivated in the proper way).
  • Alternate History: The series takes place in a setting where global warming has already melted enough of the ice caps to flood the world's coastlines, necessitating a massed relocation of urban populations before the Fleet of Fog begin their global blockade. Prior to this, the development of high-mobility, supercavitating torpedoes starting in 2012 has revolutionized naval warfare, necessitating a complete rethink of ship design and combat doctrine.
  • Aluminium Christmas Trees: Apart from rocket propelled torpedoes, the JMSDF attack submarine Hakugei has a rocket propulsion engine. DARPA has been researching adapting rockets to submarines for the last 10 years.
  • Applied Phlebotinum: The Fog Fleet is made of nanomaterial which can be formed into anything from hull plating to laser cannons as well as Mental Models.
  • Author Appeal: Want badass battleships and gorgeous women? The battleships are the gorgeous women!
  • Armor-Piercing Attack: Corrosive Torpedoes are able to penetrate Klein Fields.
  • Barrier Warrior: When separated from their ships, Mental Models fight through manipulation of their Klein Fields, for example slamming enemies away with a high-speed Beehive Barrier.
  • Beehive Barrier: The 'Klein Field' shielding used by the Fleet of Fog tends to take this form when blocking fire. Oddly enough a similar effect is seen when using the Wave Motion Gun on the I-401.
  • Big Damn Heroes:
    • The first chapter opens with one of these crossed with a Gunship Rescue, having Iona atop the I-401 rising up from the water and crushing a concrete pier to save her captain and his charge, terrify the living daylights out of some gangsters, and cause some property damage to boot!
    • Iona does this for Haruna, Kirishima, and Makie in episode 6 of the anime, after Haruna pleads for someone, anyone, to save them from the soldiers attacking them. While Haruna could have easily killed them all, she took great pains to avoid killing them for Makie's sake.
  • Black Box: Most of the Fleet of Fog technology is described as this. Even though they had I-401 in their possession, neither the Japanese government nor its crew actually know how its specific components work. One example is the Corrosive Torpedo, which they have a very limited amount of and have no means of reproducing.
  • Bland-Name Product: Jenga? Or Genius?
  • Boobs of Steel: Yamato, Nagato and Hyuuga, three of the most powerful battleships in the Fleet of Fog, have very well-endowed Mental Models.
    • Subverted with Kongou, who is probably nearly as powerful as Nagato, but flat (And according to the omake, jealous). Musashi is an even greater subversion, being the equal of Yamato but has a child for a Mental Model.
  • Breakout Character: Heavy Cruiser Takao is literally the most popular character. She's taken over the fandom so much that she's become the face of most advertisement, and she's on the anime's title splash for Crunchyroll. Even Ark Performance was surprised at her popularity, and in a magazine interview revealed that they had much different plans for her, but had to change their minds as a result.
    • It says a lot about Takao's popularity that she's been given her own spinoff in Salty Road, which tells about her experiences infiltrating human society as "Aoki Takao", a student at the elite National Maritime Institute.
  • Bring Help Back: The I-401 is setting out to America for this purpose.
  • Brits with Battleships: The Fleet of Fog also emulates the Royal Navy. While the bulk of the British-styled ships are in Europe, battleship Prince of Wales, the battlecruiser Repulse and several destroyers (including Vampire) are stationed in Asia, matching their historical deployments.
  • Cannot Spit It Out: In Chapter 21, after much preparation, Takao confronts Gunzou, intending to ask him to become her captain... and instead demands the vibration warhead and data.
  • Cast of Snowflakes: There's great variety in cast members, both in body types and facial features. This extends to background characters as well, making recurring ones easy to spot.
  • Catch Phrase: Haruna has "Entry tagged. Categorized. Recorded." while Ars Nova's Maya has "It's a carnival!"
  • Class Representative: Hiei. We kid you not. She's organized her whole cruiser squadron as a student council, with uniforms to match.
  • Creepy Child:
    • Iona has occasional shades of this. This effect is amplified with the mental models of 400 and 402. Completely averted with Iona and Takao's mini versions, who are moe incarnate.
    • Invoked with Musashi, especially in chapter 48.
  • Combining Mecha: Fleet of Fog warships are capable of doing this. Takao linked up with I-501 in order to improve her anti-submarine capability, while Kirishima and Haruma combined both of their Super-Heavy Cannons into a single massive Wave Motion Gun.
  • Cool Ship: This whole manga is an ode to cool ships of World War II, rebuilt with incredibly advanced capabilities. The Japanese-built Hakugei 3 deserves special mention for being the one human ship capable of facing the Fleet of Fog and surviving. Thanks to its modular construction it can be quickly refitted for very different abilities, like the Lightning Bruiser Assault Mode and the stealthy, long-range Cruiser Mode.
  • Cool Mask: First Mate Sou has two; the first allows him to interface directly to 401's systems, likely equipped with a Heads-Up Display. He has a second, smaller one to use when maintaining the first. The reason for the mask has yet to be revealed, although the presence of what looks like a respirator and oxygen supply hints it may be medical (in Ars Nova he makes the hasty excuse that it keeps his allergies in check).
  • Cozy Catastrophe: There are a few countries that are managing all right despite the global blockade, either because they're large enough to be self-sufficient or have neighbors with land borders they can trade with.
  • Crapsack World: The current situation is strangling Japan to death economically (see Easy Logistics), and Europe is in the midst of a major war. One way or another, every nation on Earth is feeling the effects of the blockade.
  • Curb-Stomp Battle:
    • Humanity suffers an only recently broken string of these from their early encounters with the Fog ships to the present.
    • I-401 delivers one to a fleet of over 20 Fog ships in episode 11.
  • Cyborg: Extensively used by the Northern Japanese government as special forces troops. They pull a Gunship Rescue of Makie after the Central Japanese army troops finally start overwhelming Haruna.
  • Defeat Equals Friendship: More like Defeat Equals Crush:
    • Hyuga defects to Gunzou's force after being defeated, due to her fixation on Iona-sama.
    • Takao looks likely to become this as well, on top of her Stalker with a Crush attitude towards Gunzou.
    • Haruna and Kirishima help (in anime only) Iona and Gunzou out after the latter help save them from soldiers attempting to kill Makie.
  • Deflector Shields: Fog warships of destroyer scale and larger have "Wave-Motion Armor" that is nearly impossible to penetrate without Corrosive Torpedoes or lots of firepower. Notably, small torpedo boats and aircraft are too small to be equipped with the armor, but Mental Models can generate personal shields just fine.
  • Did You Just Punch Out Cthulhu?: The Hakugei III becomes the first human made ship to sink not only one, but TWO Fleet of Fog battleships. Granted, they used stolen Fleet of Fog tech, but it was still a very big deal.
  • Eaglelanders: The remnants of United States Forces Japan. Though they've long been isolated from their homeland, it's pretty clear that they retain their American traits; even their character designs (or at least Cruz's) are distinct from the Japanese cast members. Initially presented as Boorish with their own agendas, they've since shifted into Beautiful (or at least Mixed Flavor with a positive bias) territory, being otherwise trustworthy and indirectly supportive of Blue Steel and Kamikage against Kita's faction of the Japanese government. One would expect this to be a result of leftover loyalty to America, but according to their commander, they're loyal to Japan and now consider it their home countrynote . In that regard, their motives are still questionable, but one has to admit this is a switch from usual depictions of Americans.
  • Easy Logistics: Completely subverted. The Fleet of Fog's interdiction of sea and air transport routes has crippled Japan's economy, being an island nation reliant on trade (a repeat of what happened in WW2). Nations across the globe have been similarly affected; only a handful of nations that are completely self-sufficient or have trade routes over land have weathered the blockade.
    • Subverted again with Zordan's fleet. To keep his midget sub force constantly supplied (they can only carry two torpedoes each), he has to drag around an automated Type XIV Milchkuhnote  U-boat for reloading and nanomaterial revitalization. This turns out to be the one major flaw in his strategy, as later on the I-401 snipes the Milchkuh with an enhanced Wave Motion Gun, thereby depriving the U-2501 of its main ammunition and fuel source and forcing it to prematurely withdraw.
  • Elaborate Underground Base: The Japanese Navy operates at least one heavily fortified, underground drydock built to protect what's left of the Japanese fleet from the Fog. Blue Steel maintained one on Iwo Jima, managed (and greatly expanded on) by Hyuuga, later abandoned after it was compromised.
  • Enemy Civil War: The Fog Fleet isn't as unified an entity as it was a decade before, as the creation of Mental Models has given rise to individual personalities among its ships... and they don't always agree with each other. Depending on who you ask, there are as many as six different factions in the Fog Fleet alone, all with different aims and at times working at cross-purposes: of particular note, the Scarlet Fleet under Musashi and Shouzou Chihaya seek to weld the Fog with human crews, ostensibly to fulfill the Admiralty Code's unfinished orders; they are directly opposed by a faction under Hood, who aims to stop Chihaya's ambition as usurping the Admiralty Code's authority.
  • Evolving Credits: Each episode of the anime features brief clips of that episode's contents during the opening credits. Additionally, Kirishima's teddy bear shows up when she's shown onscreen during the opening after she gains control of it. The compilation volumes for the manga have their own version: each volume adds another character to the group shot on the back cover, usually someone introduced that volume.
  • Frickin' Laser Beams: Standard weapons of the Fleet of Fog, any gun seen on a Fog ship will shoot these rather than shells. Often abused as Beam Spam.
  • Foreshadowing: The Japanese Army hopes to regain control of Iona by eliminating her crew in Chapter 31. Lt. Cruz Herder was in a position to do the very same thing in Chapter 2.
  • Four Is Death: The fire had to hit Facility No. 4 and cause a lot of fatalities, of all places.
  • Game Breaker:
    • In-universe, the weapons, armor and shielding of the Fleet of Fog fall right into this trope. Humanity's combined fleets couldn't put a dent in them 17 years ago.
    • Before the Fog showed up, it was the introduction of practical supercavitating torpedoes. Torpedoes capable of going more than 300 knots rendered conventional naval design and tactics obsolete almost overnight. Ironically, in the real world, supercavitating torpedoes aren't yet gamebreakers, as their high speed is achieved at the expense of target tracking ability (the Shkval is an unguided torp) and range - 13km for the VA-11 Shkval, vs 38km for the ADCAP.
    • In the Anime, various Fog Fleet Mental Models, especially Kongou, make note that 17 years ago, they could easily defeat Humanity in any engagement through sheer-brute strength. However, with I-401's mysterious defection to humanity's side (or rather, Gunzou's side), and the defeat of Hyuuga, they've come to realize that the threat to them, is having to face humanity using Fog Fleet strength weapons, or Anti-Fog weapons, with the advantage that humanity is skilled at tactical planning, unconventional and guerrilla warfare, and improvising on the fly. To the point that part of Kongou's reasons for wanting to engage Gunzou is to learn from the battles to collect tactical data.
  • Gender-Blender Name: Takao, Kongou, Musashi, etc. are not normally used as girls' first names, although in a partial subversion the characters are named for historical ships which are themselves named after locations across Japan.
    • Played straight with Bismarck which had always been explicitly referred to as a 'he' by its commander Capt. Ernst Lindemann and the Kriegsmarine. It still has twin girls as mental models.
    • Hand Waved also in that the Mental Models explain this has to do with the fact that humanity almost always treat ships as feminine, and using female pronouns when referring to them. That's apparently the only justification they have, and it's not delved into any further.
  • Godzilla Threshold: Humanity has reached such a desperate point that they're willing to try anything in an attempt to fight off the Fog ships. Japan in particular has evidently suspended some human rights in order to relocate or just abandon certain parts of its population and later engineered select Artificial Humans to handle such decisions in future.
  • Gravity Master: Given the feats displayed by Haruna without the assistance of her ship, all Fog mental Models are probably this as standard. Also combines with Barrier Warrior and Voluntary Shapeshifting.
  • Hammerspace: Played with on the Fog Fleet ships. It's for the most part averted, and justified in that while they look like WWII-era ships, that is merely on the outside. With no need to concern themselves with crews, the ships can devote more space to armament, munitions, and power supply.note  Other aspect of the ships armament, is explained as manipulating the Nanomaterials to alternate the ship, or its armaments configuration on the flynote  That said, their solid munitions available, plays this straight, with the surface ships simply popping open more missile tubes as needed. Ammunition storage is only mentioned when needed for drama for the most part.
  • Humans Are Special mixed with Bastards: Yamato is keenly aware the only reason the Fleet of Fog is dominating the world's oceans is because of their Game Breaker technology and the moment humanity catches up, which will eventually happen, human tactics and strategy will mean the Fleet of Fog is screwed.
  • Imagine Spot: In chapter 9 of the manga, Takao reads a children's book about sea captains. The result is... Interesting.
  • Impact Silhouette: Makie first meets Haruna after the latter has blown a human-shaped hole through a warehouse wall.
  • Interservice Rivalry:
    • Due to the nature of the conflict with the Fleet of Fog, the Japanese Army has largely been ignored in favor of the Navy, much to their chagrin. This is the primary motivating factor why they've aligned with Kita, since they're desperate to win some recognition.
    • Even the Fog have this, as certain ships of the Oriental and Europeannote  fleets hold subtle but distinct animosity toward each other. The best example of this is shown in recent chapters, where I-402, seemingly on orders from Yamato, actively supported both Takao and I-401 in fighting U-2501. And before that, there were assorted scenes of Oriental ships not being keen on U-2501's presence in the pacific, nor Souzou Chihaya holding command of the European Fleet in general.
    • Even within the Japanese government. When the Japanese government learns Haruna is spotted at Makie Osakabe's home, Central Prime Minister Mitsumine gives the Army the green light to assassinate Makie to prevent the Vibration Torpedo's plans being revealed to the Fleet of Fog. However, Makie is the Northern Prime Minister Makoto Osakabe's younger sister, and he sends cyborg commandos to help Haruna and rescue Makie.
    • The Japanese Army and Navy really don't get along very well; at one point, a firefight nearly breaks out between Navy SEALs and Army soldiers.
      • This is Truth in Television. During World War II, the Japanese Army and Navy often had to compete for resources and as a result absolutely despised each other. They would even go so sabotage each others' projects during wartime for no other reason but pure spite. And in the decades prior to World War II, both services were assassinating each others' officers.
  • Ironic Echo: Gunzou uses one in his dinner conversation with Ryokan Kita.
  • Is This What Anger Feels Like?: A recurring theme as the Mental Models gain experience, especially those who have faced and lost to humans.
  • Kaiju Defense Force: The Japanese Maritime Self Defense Force and Ground Self Defense Force are upgraded into an official Navy and Army against the Fog.
    • Gunzou Chihaya was originally an officer cadet, and his father was a JMSDF Commander, who was the first captain of I-401 after she was captured by the Japanese Navy.
    • The JMSDF appears in several instances, being mostly helpful to I-401's crew - it helps that the CNO was a friend of Souzou Chihaya. The prototype submarine Hakugei assists in I-401's takedown of Kirishima and Haruna.
  • Katanas of the Rising Sun: So far, most ships seen in the Fog Fleet's Oriental Fleet are Imperial Japanese Navy vessels.
  • Laser Sight: Averted. The snipers are using infrared beam which are invisible to the human eye. This makes a lot more sense than optical lasers.
  • MacGuffin: The series actually has two: The vibration torpedo which must be smuggled to the United States to be mass produced, and the "Admiralty Code" that the Fleet of Fog is looking for.
    • Living MacGuffin: Given how the Admiralty Code has been depicted as having a Mental Model of its own (a young woman wearing an old-style Apollo astronaut's rig), it could be seen as this as well.
  • Macross Missile Massacre:
    • One of the tactics used by Takao, who puts up an impressive volume of fire for a mere heavy cruiser. She's later on the receiving end when approaching Iwo Jima.
    • Ships of the Fleet of Fog only look like they're from World War II. Being made of nanomaterials means they can reconfigure portions of themselves to carry and launch truly absurd numbers of missiles and torpedoes. It's actually quite rare that a Fog ship launches any less than two dozen missiles or torpedoes at a time.
  • Mugging the Monster: A Mental Model without her battleship. An entire army division sent to capture her. What could possibly go wrong?
  • Nanomachines: Also commonly referred to as "nanomaterial", the Fleet of Fog is made entirely of the stuff and it's the source of all the Game Breaker technology they use. Where it all comes from is one of the many mysteries surrounding the Fog, but samples were found in sea water as early as the 1920s according to the supplementary material.
  • Nazis with Gnarly Weapons: The Fleet of Fog's European forces include Kriegsmarine vessels ranging from the battleships Bismarck and Tirpitz to the Type XXI U-boat U-2501. The latter is commanded by Zordan Stark, a German (possibly Danish) protegee of Gunzou's father.
  • Never Found the Body: Light Cruiser Nagara was sunk in Chapter 1, sixty-plus chapters later the Fog is still trying to find out where her core went.
  • Nigh Invulnerable: Fleet of Fog ships are almost impossible to damage because they suck the energy of incoming attacks into a "Klein Field". The Klein Field can be collapsed if it's pumped full of enough energy, but that takes an incredible amount, and the ships can release energy from the bottle at will. Even without the Klein Field, nanomaterial armor is very hard to crack short of corrosive torpedoes.
  • Noodle Incident:
    • Everybody talks about how the I-401 and its crew sunk the Hyuuga, but we've never actually seen the battle nor have we been given an accurate summary of events.
    • The fire at Facility No.4 of the naval academy Gunzo went to. The only thing sure is that Kotono is supposed to have died there.
  • Orcus on His Throne: The Fleet of Fog are shown to be perfectly capable of wiping out literally every coastal city on the planet (which basically means all of Japan). However, they're mostly content with just sitting back and maintaining the global blockade. Revealed by Yamato later on to be one of the orders given to the Fog Fleet by the Admiralty Code. Many among the Fog are now wondering why this is so.
  • Oh, Crap:
    • Lawrence, Makie's butler, has this reaction when he learns that the friend Makie brought home is Haruna's mental model.
    • Iona has data on all the ships belonging to the Oriental Fleet, of which she is a former member. Her admission that she has no data about U-2501 provokes one of these from her crew.
  • Ojou:
    • Yamato gives off this vibe, what with being a Yamato Nadeshiko.
    • As does Amaha Kotono, who is effectively Yamato's human twin and may or may not still be alive.
    • Kongou also has shades of this, which is accentuated in the anime.
  • Ontological Mystery: Where did the Fog come from, why do they take on the forms of World War II warships, and why were they ordered to blockade the seas in the first place? They don't know either. If the missing "Admiralty Code" can be found, answers might be forthcoming, but the Fleet of Fog is already starting to fracture on the issue of if they even want to know.
  • Outside-Context Villain: The Fleet of Fog in a nutshell. Nobody saw them coming and it's taken nearly twenty years to come up with anything close to countering them.
  • Painting the Fourth Wall : In chapter 18 Haruna scanning aside of Makie brain, hands and hairs also her Speech Bubbles
  • Phlebotinum Analogy: The explanation of how the Klein Field works as First Mate Sou was doing right before he was kidnapped.
  • Preemptive "Shut Up": Used by Captain Komaki when, in a panic, he tried to ask out Maruri — who is half of his age — on a "date" in front of his crew.
  • Pretty in Mink: Musashi, in her guise as a Russian Snow Girl.
  • Putting on the Reich: Zordan dresses in the traditional style of a U-boat captain, i.e. Badass Longcoat and Commissar Cap. When not wearing those items, he wears a jacket that's fashioned off the flag of Denmark.
  • Reality Is Unrealistic:
    • One of the more common human weapons is a rocket-propelled torpedo. Such weapons have been in service since 1998.
    • Hakugei uses a rocket engine to achieve supercavitation. This is currently under research by DARPA.
  • Reasonable Authority Figure:
    • Both Kamikage and the Prime Minister are willing to help the I-401 in any way they can, especially when a large portion of the Japanese government is out to try and thwart their plans.
    • Makoto Osakabe, the minister of Hokkaido, is perfectly willing to let Haruna, Kirishima, and Maya be, though he does admit that he will eventually have to put on a token amount of resistance to save face once they are ready to leave port.
  • The Reveal: Yamato's mental models are the spitting image of Kotono Amaha, one of Gunzou Chihaya's supposedly dead Childhood Friends and likely love interest. Made all the more effective by introducing Yamato first and leaving Kotono's appearance vague until the reveal.
  • Right Hand Versus Left Hand:
    • On one side in the Japanese government is Assistant Secretary Ryuujirou Kamikage who wants to use the I-401 to transport their most successful man-made weapon that is capable of destroying a Fleet of Fog ship to the United States, so it can be mass produces, and has the support of the Japanese Navy and the local US forces. On the other side is the powerful Tycoon and top candidate for Prime Minister Ryoukan Kita, who wants the I-401 returned back to the Japanese Government so they can reverse engineer it and make their own Fleet of Fog ships, and who has strong contacts withing the Japanese Army.
    • At one point, an Army company under Kita's influence seizes the I-401's dock and arrests the crew; the Navy SEALs came very close to starting a firefight and rescuing the crew by force, before both sides were ordered to stand down.
  • Robot Maid:
    • Several run the Osakabe mansion and are realistic enough that they aren't revealed as such for several chapters.
    • Saori Chihaya's maid is another robot who's personality has apparently broadened considerably since Takao started hanging out with her.
    • Battlecruiser Repulse's mental model is an English maid. She takes the maid persona so far that she actually repairs her battle damage by sweeping.
    • Vampire's Mental Model follows the same theme as her flagship, except in a child-sized short skirt version. This is coupled with some appropriate vampire themes, namely Cute Little Fangs and a bat shaped pendent on her uniform collar. Overall she looks like something out of a Tim Burton movie.
  • Rotating Protagonist: The character focus switches so much that it's hard to seriously believe that Gunzou and the crew of Iona are the heroes here. Several Fog ships have shown more obvious character development.
  • Rubber Face: Iona to Iori.
  • Scenery Porn: Ark Performance shows what drawing Gundam manga for years does for skill at drawing mecha and landscapes. Higher resolution versions of the manga are recommended to see just how much detail they put into everything.
  • Screw the Rules, I Have Money!: Invoked by Makie when a cab driver attempts to protest the apparent little girl trying to catch his cab by herself. His reaction to her SPECIAL GOLD CASH CARD is priceless.
  • Shout-Out: All of the Fleet of Fog ships are replicas of real life WWII era warships, all part of the Ontological Mystery surrounding their origin.
  • Show Within a Show: Hisonic Miku-chan, an anime popular with Makie Osakabe, Kyouhei and Iona.
  • Spaceship Girl: Fleet of Fog ships of heavy cruiser class and up (including the I-400 class submarines) can have a "Mental Model", which represents the AI controlling the ship. Unusually for this trope, Mental Models weren't intended to interact with a crew, but rather to help the ships to develop more humanlike tactics and strategies through the imitation of human limitations and perspective. The largest battleships with greater computation capabilities (i.e. Yamato, Nagato, Bismark) can have two, sometimes with distinct personalities from the other. Iona and Takao can also create miniature versions of themselves who have some measure of autonomy and can be used for shipboard tasks (or just be adorable).

    The actual Union Core that houses the Mental Model for each ship is actually quite small: Kirishima survives her destruction by throwing her own core to Haruna; Makie is able to pocket it later quite easily. Cores devoid of nanomaterials to interface with are completely helpless: Kirishima spent some time in Haruna and Makie's pockets; Haguro's core was swallowed by a shark for a short while until salvaged by Ashigara.
  • Spider Tank: The Japanese army has a four-legged type called a "Rock Crab". They'd probably be quite formidable if they weren't fighting a very angry Haruna.
  • Stalker with a Crush: Takao is pretty quickly turning into this for Gunzou.
  • The Pirates Who Don't Do Anything: Because aircraft are too small to mount Klein Fields or other Game Breaker tech, air defense is the one area where humanity can actually defeat the Fleet of Fog. As a result aircraft carriers like Zuikaku have lost most or all of their planes and are stuck being really bored. Zuikaku herself passes the time by fishing and cooking what she catches.
  • Transforming Mecha: The Fog Fleet ships are all replicas of WWII warships, but only on the outside—under that is their advanced weaponry that they rearrange on the fly.
  • Tron Lines: Fog ships tend to be covered in glowing patterns like tattoos.
  • Twenty Minutes into the Future: The first battles with the Fleet of Fog are in 2038. The Great Naval Battle which almost entirely wiped out the world's navies happens the year after. The actual series begins in 2056.
  • Unobtainium: Thanatonium used for Fog Fleet corrosive torpedo/missile warheads.
  • Unskilled, but Strong: The fleet of Fog is a good example of this. Their Game Breaker technology is the source of their victory over humanity — if humans had it, they would have won through superior tactics. They are however very fast learners. As the story goes, Fog ships begin to work on developing tactics, though they still have a bias towards efficiency (this comes to bite Takao in the ass when she reveals her hand in her first engagement with Gunzou).
  • Villainous Rescue: Haruna and Kirishima's attack on Yokosuka provides a very convenient excuse for Gunzou to escape from Ryokan Kita's attempts to steal I-401 away from him. That he also successfully defeats both of them helps as well.
  • Walk, Don't Swim: The mental models of the Fog ships are fully capable of walking on the bottom of the ocean if they want to.
    • Zuikaku claims she sometimes swim, sometimes walk on the sea floor to get between her ship and the shore.
    • When Ashigara goes to look for a sunken ship, she takes a stroll in the depths.
  • Wave Motion Gun: While the Fleet of Fog on the whole has dramatically superior armaments and shielding to the human fleets, Heavy Cruisers and larger have access to Super-Heavy Cannons that are exactly this. Battleship-class vessels come equipped with 'Super Gravity Cannons', which despite the name fill the trope nicely, since the weapon tends to bend space around it and it's firing path.
  • We Can Rule Together: After cornering the 401 and its crew, Zordan suggests Chihaya to join the Fleet of Fog under his boss, Chihaya's father.
  • What Measure Is a Non-Human?: When Gunzou realizes that some of the Fleet of Fog ships are self aware like Iona, he decides to spare Takao rather than kill her.
  • Wolfpack Boss: Appropriately, Zordan's strategy. Alongside the U-2501, he also commands a force of automated midget subs known as the Seehund (Sea Hounds), which he uses as forward attack ships. Alongside, he can sacrifice several of these subs to create functional replicas of the U-2501, complete with torpedoes and other special features.
  • Yanks with Tanks: The US Pacific Forces who were stranded in Japan; as Fleet of Fog interdiction of air and sea routes makes returning them to the US impossible, they've been absorbed into the JMSDF as the Unified Forces. There is also a portion of the Fleet of Fog patterned after the historical US Navy that's patrolling the Americas, they make their first appearance after Chapter 64.
  • You Are Number Six: I-401 is the ship's initial designation, though her mental model is called Iona by the/her crew. Later on, we find she's one of a series of submarines, as we meet 400 and 402, who look exactly like her, though dressed differently. Also there's I-501, who was spotting for Takao, and U-2501 who's from the Atlantic Fleet.

    Tropes unique to Ars Nova 

  • All-CGI Cartoon: Of course.
  • Batman Gambit: When escaping from Iwo Jima, Kongou becomes obsessed with killing Gunzou, believing that he's the reason why several of the Fog ships formerly allied with her have done a Heel-Face Turn. While Iona attempts to escape through a carefully plotted route along an minefield, Kongou suffers massive damage pursuing Iona and Gunzou, while barely paying any attention to Takao's ship. After a successful hack by Hyuuga, she manages to divert Kongou's second attack from hitting Iona, and only then does Takao tell her former boss that the vibration torpedo was actually aboard her ship, and Iona was actually a decoy. Unfortunately however, Iona is attacked by I-400 and I-402 shortly after they escape from Kongou.
  • Beach Episode: Part of the 7th and 8th episode.
  • BFS: Kongou uses one on Iona in episodes 8 and 12.
  • Big Damn Heroes: Iona, of all people.
  • Body Horror: By Fleet of Fog standard, anyway. Kongou devours a huge number of Fog ships to become something that can't be called a ship, a serious transgression against Admiralty Code. Ironically, this is due to her obsession to destroy Iona which she sees as a stray.
  • Broad Strokes: The anime isn't really following the manga faithfully, to say the least.
    • Adaptational Villainy: Assistant Secretary Kamikage is far more ruthless in Ars Nova, personally ordering the assassination of Makie just to prevent the Fog from getting the secrets of the torpedo she created. Later it is revealed it was part of Kamikage's plan to have the I-401 crew to rescue and bring Makie with them.
      • Maya was never shown to have fought human-aligned forces in the manga (instead playing chaperone to both Haruna and Kirishima), however the anime has her join Kongou against her sister ship Takao and her allies in the Blue Fleet.
      • As the left and right hands of Yamato, I-400 and I-402 were never in opposition to Iona, and since they were loyal to Yamato, didn't even pay lip service to the Admiralty Code. In Ars Nova however, they seem to be unthinking drones loyal to the Admiralty Code, even more than Kongou... to the point that they attack Iona just as she escapes Kongou, detain Kongou due to her hate making her deviate from Admiralty Code, reveal Maya to be a fake Mental Model....
    • Adapted Out: The fate so far of Yamato, Kotono Amaha, Lawrence, the Hakugei, the mini Mental Models...
    • Crapsack World: Humanity is even worse off in the anime than the source material: in the manga radio communications still work and some satellites remain in orbit to relay messages around the globe, America can even send sporadic aid via rocket; in Ars Nova the Fleet of Fog's grip is even tighter and is jamming all communications as well. Gunzou and crew are embarking on their trans-Pacific journey without being sure America is even waiting for them.
    • Composite Character: To a degree, this is what happened. The most apparent instances so far are Yamato's lines and role being given to Kongou, and Kamikage takes the role of the perpetrator of the attack on Osakabe household instead of Kita (though in the manga Kita wasn't the one who initiated it, he only takes the blame). Makie also gains her older brother Makoto's dependency on special medications to be able to digest the food she eats. Lastly, while this is dubious (as her full capabilities has yet to be disclosed), Iona in Ars Nova also gained the 'overdrive mode' employed by Hakugei in the manga.
    • Death by Adaptation: Maya, as it turned out, never was alive to begin with by Mental Model standards, and I-400 and I-402 are sunk in battle with Ars Nova I-401. To a lesser extent, this happened to Saori and Shouzou Chihaya (except not really) as they died in the Facility No.4 fire.
    • Pragmatic Adaptation: A whole lot of plot points are excised outright from the anime adaptation, likely due to the 12-episode constraint the show has to deal with. This includes but is not limited to: the survival and Face-Heel Turn of Gunzou's father, Gunzou's mother Saori and her later interaction with Takao, the destruction of Institute 4, everything related to Yamato, Lawrence and the Osakabe household... The movies put Gunzou's father back in.
    • Spared by the Adaptation: In the manga, the Osakabe mansion maids are robots who were killed fighting against the Japanese Army. In the anime, the maids are implied to be possibly human or mere domestic robots, and they surrender peacefully to the Army.
  • Broken Record: Maya spouts off repeated lines after The Reveal in episode 10.
  • Cel Shading: The anime takes a mild degree of this in its CG, especially for the human characters.
  • Chekhov's Classroom:
    • In episode 4, as Haruna and Kirishima deliver a Curb-Stomp Battle to some human ships, the former overhears one man over the radio talking about not wanting to die and to be saved. She logs that definition in for future reference. In a bit of Irony, when I-401 delivers a Curb-Stomp Battle to both of them at the end of the episode, right before she's hit, Haruna also mentions not wanting to die much in the same way the unnamed sailor she heard earlier.
    • In episode 7, Hyuuga tells Takao that humans will sometimes perform a Heroic Sacrifice for the greater good, rather than think only about themselves. So when Takao searches for and finds Iona's core inside of Gunzou's escape pod in episode 10, she sacrifices her nanomaterials in order to allow Iona to reconstruct herself and allow Gunzou to survive.
  • Conservation of Ninjutsu: In episode 11, Gunzou is able to wipe out well over 20 Fog ships with one sweeping attack. Contrast that to the earlier battles where the humans on I-401 often had trouble against just one or two Fog ships.
  • Conspicuous CG: THE ENTIRE SERIES was animated in 3D CG, making the parts that are not CG conspicuous.
  • Cooldown Hug: Iona gives one to a crying Kongou in episode 12 after the former manages to breach the barriers put up by the latter.
  • Creative Sterility: The Fog have a bad case of this. Probably an Enforced Trope via the Admiralty Code. They are WWII-era battleships because they are and look female because most ships are considered feminine. Averting this is considered a very bad thing, though Mental Models were an attempt to alleviate this in the case of tactics.
  • Credits Gag/Evolving Credits: Not always, but the 7th episode has them.
  • Cry Cute: Kongou, of all people, in episode 12. When Iona finally reaches her core, Kongou is sitting down with her face buried by her knees, with tears streaming down.
  • Curb-Stomp Battle:
    • Episode 11 opens with Ars Nova versus twenty-plus Nagara-class cruisers. The battle lasted probably a minute at best.
    • Episode 12 opens with another curbstomp, this time by Kongou wiping out the American Fogship forces.
  • Detached Sleeves: Iona's outfit.
  • Despair Event Horizon: Kongou is driven to one after The Reveal that she was seen as increasingly unstable, and especially that Maya was a spy for I-400 and I-402. After she manages to free herself, she combines with Maya's ship, and fires on her own allies in her zeal to kill Iona and Gunzou.
  • Devour the Dragon: What Kongou does to Maya.
  • "Do It Yourself" Theme Tune: The ending themes and some other songs for the anime are performed by Trident, an idol-type seiyuu unit created for the show, consisting of Mai Fuchigami (Iona), Manami Numakura (Takao), and Hibiku Yamamura (Haruna).
  • Earn Your Happy Ending: In episode 12, knowing they would lose in a face to face battle with Kongou, Iona instead suggests sending her core directly onto Kongou's ship, where she could attempt to connect directly. While risky, Gunzou doesn't have any other options, and Kongou doesn't make it easy for Iona either once the latter reaches the former's ship.
  • Eyelid Pull Taunt: Hyuuga does this to Kongou (by popping up little digital faces in Kongou's HUD) in episode 9 after successfully hacking her to cause her attack on Iona to miss.
  • Faceless Goons/Gas Mask Mooks: The Japanese Army troops who assault the Osakabe mansion.
  • Fashionable Asymmetry: Kirishima's outfit in the anime, taken from what she wore on one of the compilation volume covers. She never wore it in the actual manga, and had something far more conservative on instead.
  • Fusion Dance: While some of the combinations the Fog ships can do amounts to Combining Mecha, Takao merges completely with the I-401 (while retaining her core and processing power), and Kongou merges with Maya and eight Nagara-class cruisers to form a Death Star-like zeppelin.
  • The Glomp: Takao does this to Gunzou after Hyuuga restores her mental model in episode 12. Her impact knocks him to the ground.
  • Gecko Ending: The final episode of Ars Nova amounts to this. Not only was the Vibration Torpedo, its blueprints, and its creator delivered safely to the United States, everyone is presumed to live their lives peacefully from that point on, with even Takao's Mental Model restored. Even Kongou seems to be at peace with herself. None of this happens in the manga.
  • Gratuitous English: The opening title has both English and Japanese lyrics. That said, this doubles as Surprisingly Good English as well, as the English words are easily understandable to a native speaker.
  • Happy Ending Override: The final act of the first Ars Nova movie. After the Americans successfully use a vibration warhead to destroy a Fog warship, Iona's crew use a device to disable the rest, in the hope of preventing mankind from wiping the Fog out. As one might expect, this makes them wanted criminals. They, along with Takao, Haruna, Makie, and Kirishima, have to leave the relative safety of the US West Coast... which just drops them straight into an encounter with Hiei and her escorts. And things go From Bad to Worse from there.
  • Heroic Sacrifice: Takao uses her own nanomaterials to repair a heavily damaged and sunk Iona in episode 10, but this comes at the cost of losing her ship and even her mental model. This is after she realizes Iona holds a greater place in Gunzou's heart than she ever would, but nevertheless proceeds to save both.
  • Heroic Second Wind: Iona gains one after hearing Gunzou, and finding a newfound determination to save Kongou, despite being beaten badly and subdued at the time.
  • "I Know You're in There Somewhere" Fight: Iona uses this against Kongou in episode 12. Kongou attempts to fight this, but Iona finally breaches the barriers to reach out to her core.
  • Ill Boy: Instead of masquerading as a butler, Toojurou Osakabe is this in the anime.
  • Irony: Kongou's obsession with terminating Iona and her zeal for upholding the Admiralty Code... is considered to be in violation of the Admiralty Code.
  • Improvised Platform: Klein Fields can be manipulated to be used like this.
  • Killed Off for Real: The fate for some characters in the adaptation, specifically both Gunzou's parents. Except not really on the part of Gunzou's father.
  • Lampshade Hanging: In the first movie, when Hiei starts lecturing Gunzou and co. in her self-styled student council president persona, Kyouhei says that the Fog have started speaking gibberish. The Myouko sisters also point out the oddness of wearing school uniforms.
  • Laser Sight: In episode 2, Iona surfaces the weapons-hot submarine outside the balcony, and laser pointers mark everyone who could contest their leave from an unproductive talks over dinner with Yokosuka army.
  • Late-Arrival Spoiler: The first movie openly lays out Makie's true nature, rather than building up to The Reveal as in the anime.
  • Locked in a Freezer: The plot for Episode 10. Gunzou and Iona are stuck on the ocean floor in a broken ship, the life support system gets progressively worse, and there's even frost at one point.
  • Mid-Season Upgrade: I-401 merges with Takao in episode 10. Kongou merges with Maya, turning herself into a Death Star.
  • Mooks: The poor, poor, Nagara-class ships seemed to be given this treatment in Ars Nova, especially in episode 11, where 22 of them are obliterated in one pass by the Ars Nova.
  • Naval Blockade: What the Fog ships are doing to humanity. It's never made clear exactly what the motive for doing it is however, at least in the anime.
  • Nice Job Breaking It, Hero:
    • Iona attempts to draw Kongo into conversation, talking about fun as the Mental Models hang out on the beach. This causes Kongo to solidify her resolve to destroy them all.
    Kongo: "We are weapons. Weapons have no need of fun."
    • Also, her attempts to get Kongo to feel emotions and thus break away from the Admiralty Code backfire: Kongo remains determined to follow the Admiralty Code, despite the emotion she feels. What emotion is it? Hate.
    Kongo: Remember this... I hate you.
    • This happens as part of the first movie's Happy Ending Override. After letting the Americans successfully destroy a Fog ship with the vibration warhead, Gunzou and co. activate a device that causes the Applied Phlebotinum used in the vibration warheads to stop working... and find out after the fact that the rest of the Fog aren't the slightest bit deterred by the demonstration.
  • Nice Job Fixing It, Villain: Kongou curbstomping all those American Fogships sure helped the Ars Nova crew a lot in the end.
  • Ninja Pirate Zombie Robot: Ars Nova is a Submarine Cruiser. The Kongou-Maya merge is... a little harder to define and strays to That's No Moon! territory.
  • No-Holds-Barred Beatdown: Kongou towards Iona. She doesn't hold back at all in her attempts to kill the latter in episode 12.
  • Offscreen Teleportation: In the first movie, after Gunzou and co make it to the US, Makie, Haruna and Kirishima take up residence in a house. After the rest of the vibration warheads are disabled, soldiers are sent to arrest them. After a shot showing the soldiers surrounding the house, it cuts to the trio inside the house gathering their things to escape. It then cuts to the soldiers breaching... who find an empty house. No explanation is given for this.
  • Oh, Crap: Iona gets this in Episode 9, when Kongo declares she hates her while pursuing her underwater.
  • Ominous Latin Chanting: Mostly in this song, but other background songs have shades of this trope.
  • The Only One Allowed to Defeat You: Kongou towards Iona, especially towards the end.
  • Properly Paranoid: Kongo in episode 8. Invited to a parley by Gunzou, she keeps her guard up, does not allow herself to form an emotional connection, doesn't eat or drink anything that's served to her, and kept her Union Core on her foredeck and sent a decoy body to the parley, all to avoid being contaminated by Gunzou and Iona. Unfortunately for her, it didn't quite work.
  • Shout-Out: The music video for the opening song of Ars Nova has scenes shot in front of and aboard the JMSDF ship Kirishima. In Episode 11, Kyouhei's reaction to seeing Kongou is "That's no battleship!"
  • Storm of Blades: Kongou uses this in conjunction with a BFS against Iona in episode 12.
  • Talking Is a Free Action: Several of the Fog ships find time to talk to and have tea with each other, even while actively fighting or evading each other at the time, such as when Iona tries talking to Kongou while escaping her at Iwo Jima. Justified in that it takes place in what amounts to a chat room and they are AI constructs.
  • There Is No Kill Like Overkill: Kongou sends 512 corrosive torpedos at I-401 in episode 12, while simultaneously using her Wave Motion Gun on them. When Iona attempts to reach her ship, she also sends multiple torpedos to stop her, and uses a Storm of Blades after the former manages to make it to the ship.
  • They Wasted a Perfectly Good Sandwich: Gun-toting, army men gather the I-401 crew at a served dinner table for a talk with army higher-up in Episode 2. Crew members note luxury of the meal, yet only head of the table manages to sip some wine while arguing with Gunzou, before Yokosuka port gets attacked from the sea, prompting guests to leave.
  • Title Drop: Iona reveals early in episode 11 that the Takao-Iona fusion is indeed called Ars Nova.
  • To Win Without Fighting: Iona attempts this several times with Kongou, but fails each time...until episode 12, when she successfully reaches Kongou, who was suffering from loneliness. She didn't want to kill her as she was forced to do with I-400 and I-402 earlier.
  • Too Dumb to Live: 400 and 402 shows shades of Artificial Stupidity towards the series' end. First, they detained Kongou aboard her own ship. Second, they should be employing ambush tactics when going against Ars Nova... instead, they attacked her head on knowing that Ars Nova has a whopping five cores on board.
  • Trailers Always Lie: Contrary to the movie promotional material, Hiei and the Myouko sisters never appear onscreen at the same time, with the former's escorts being the light cruisers (and hence Mental Model-less) Natori and Yura.
  • Villainous Rescue: In episode 12, I-401 is getting close to the US, only to get confronted with the massive US Fog Fleet in front of her, and an overzealous Kongou with an upgraded ship/death star. The latter then fires her Wave Motion Gun, only to wipe out the entire Fog Fleet in front of Iona. Several of the characters wonder if Kongou deliberately missed, but when they ask, she states in a monotone voice that it's to avoid corrupting them the same way Iona seems to have corrupted her fleet.
  • Violence Is the Only Option: The attempted parley with Kongou only serves to convince Kongou to wipe Gunzou and his friends off the face of the planet. She continues to use this in her attempts to wipe them out, despite Iona's pleas and attempts to reach out.
  • Wham Episode: Episode 9 ends like this when having barely escaped from Kongou, Iona and Gunzou are ambushed by I-400 and I-402 just when they were proverbially catching a breath.
    • Episode 10 topped it by Takao sacrificing herself to restore Iona back, revealing that Maya is a fake simulacrum made by I-400 and I-402, and detaining Kongou of all people.
  • You Are Not Alone: Iona finally manages to reach Kongou, who up till this point had gone berserk and attempted to kill the former repeatedly. Once Iona manages to reach Kongou's core, she gives her a Cooldown Hug, and tells her she's not alone.


Alternative Title(s):

Arpeggio Of Blue Steel