History Anime / HighSchoolFleet

[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/hai_furi_a.png]]

[[AlternateHistory A hundred years ago]], tectonic forces plunged most of Japan's landmass underneath the oceans. Coastal cities became the norm, which then evolved into marine cities, massive seaborne settlements that were part-city and part-seagoing vessel. [[AllThereInTheManual In order to safeguard these oceangoing metropolises, the national maritime forces had to expand]], which in turn offered more opportunity for women to advance in what what were traditionally masculine roles. In time prestigious all-women outfits like the Blue Mermaids became every young girl's dream job.

Akeno Misaki, nicknamed "Mike", is one of these hopefuls, and enrolls in the prestigious Yokosuka Girl's Marine High School in the hope of one day joining its ranks. There she meets up again with her ChildhoodFriend Moeka China, who is now the captain of the training ship Musashi. Moeka would also want to one day join the Blue Mermaids, so who among the two friends will reach her dream first?

''High School Fleet'' (ハイスクール・フリート), also known as ''Hai-Furi!'' (はいふり), is an AnimeFirst series by Creator/ProductionIMS that premiered during the Spring2016Anime season. It features character designs by Atto (of ''Manga/NonNonBiyori'' fame), as well as many of the staff that were part of Anime/GirlsUndPanzer's production.

* ACupAngst: In episode 6, some of the girls in the Engineering Dept react badly as they see Wilhelmina's [[https://media.giphy.com/media/trq4NCEbDsW3K/giphy.gif larger assets]].
* AlternateHistory: In this case, the point of divergence took place right after the Russo-Japanese war of 1905, as the subsidence of Japan took place sometime after it due to excessive mining of Methane Hydrate. A later interview in [[WordOfGod May 2016's issue of Model Graphix]] reveal that, among things, UsefulNotes/WorldWarI and UsefulNotes/WorldWarII still happened, but slightly differently, both because Japan never participated in either (due to the aforementioned subsidence of its landmass) and the fact that heavier-than-air flight technology was never developed in-universe, because the people in this timeline decided that it was a line of research that was just too impractical to pursue.
-->'''Kouko:''' ''[looking at the birds flying by]'' At times like this, I wish we could fly back to school like that. ''[turning to Mashiro]'' I wonder if you can make a flying ship without hydrogen or helium?\\
'''Mashiro''' ''[sighs]'' Only in your imagination. Ridiculous.
** [[FridgeLogic So why do the ships have anti-air batteries?]]
* ArtisticLicenseGeology: The explanation given by Mashiro's mother for the reason for the subsidence of Japan's landmass being partly due to the over-mining of the undersea deposits of Methane Hydrate doesn't make any sense. There's a chance that she was genuinely misinformed, however.

** The default armament of the ''Independence''-class LCS is a [[https://en.wikipedia.org/wiki/Bofors_57_mm_gun Bofors mark 110 57mm gun]]. This was accurately shown for the first half of episode one. However by the second half, it seemed to have spontaneously morphed into a [[https://en.wikipedia.org/wiki/5%22/54_caliber_Mark_45_gun 127mm/L62 Mk 45 Mod 4]], which is the standard weapon of the ''Atago''-class of guided missile destroyers used by the real-world JMSDF. The rate of fire it showed (an almost casual 20 rounds-per-minute) [[spoiler:when it attacked the ''Harekaze'']] also matched up with the Mk 45, as a Bofors 57mm would have instead put out a blistering ''200+ rounds per minute''. In addition, the LCS is shown having its standard flight deck for helicopters and [[https://en.wikipedia.org/wiki/RIM-116_Rolling_Airframe_Missile SeaRAM point defense missiles]] above the helo hangar, even though it's explicitly stated that heavier-than-air flight does not exist in this universe. Episode 7 throws this and the ''Akizuki''s supposed lack of reason for existence in for a loop due to the appearance of an airship.
** The I-201 running underwater at a sustained speed of 20 knots is nearly unheard of. While the historical [[https://en.wikipedia.org/wiki/I-201-class_submarine Sentaka-Dai]] submarines could ''theoretically'' go faster, most would never go over 19 knots for safety and practical reasons, for the simple fact that it would break the engines if they tried.
** The ''Akizuki''-class destroyers fighting the ''Musashi'' attempt to use [[https://en.wikipedia.org/wiki/RUM-139_VL-ASROC ASROC missiles]] to disable her, even though ASROC traditionally is an anti-submarine weapon and not intended to be used against other ships.
* AudienceSurrogate: Kouko Nosa. In fact, the little spiel she gave at the start of episode two reflects ''the'' most popular theory that came out of the Japanese and Western viewership in the wake of episode one.
* BeachEpisode: Episode 5 somewhat like this.
* BigDamnHeroes: The ''Harekaze'' and the Blue Mermaid fleet pull this to save the ''Musashi''.

* BookDumb: Mike admits that her grades aren't that good, and she's convinced that the was only able to get a captaincy because she crammed before the exam. This however doesn't stop her from being a competent skipper when the need arises.
* BornLucky: Mike has been blessed by an ungodly degree of luck. This manifests in the improbable successes that the damaged and outgunned ''Harekaze'' was able to gain over its opponents, as well as in more mundane situations, like ''winning a year's supply of toilet paper'' at a lottery, just when the crew really REALLY needed it.
* BornUnlucky: Mashiro seems to think that she's this. She gives the Fusou sisters from VideoGame/KantaiCollection a run for the money with how much she repeats how unfortunate she is. She does have several accidents, such as falling to water, getting splashed by water guns, and other mishaps, so her concerns aren't unfounded.

** Episode 4. There's no big battle, and most of it is spent on the crew just relaxing for a change, while Mike takes an away crew to a ocean-based shopping mall to acquire supplies.
** Episode 10 as well, as the Harekaze is repairing the girls relax and celebrate at crossing the line.
* TheCaptain: Mike's actual position, although unlike Moka's position commanding the Musashi, she's the skipper of a simple destroyer, the ''Harekaze''.
* TheCavalry: The other school ships and the ''Graf Spee'' arrive to assist the ''Harekaze'' in stopping the ''Musashi'' just when Mike was about to give the evacuation order in the final episode.
* CastOfSnowflakes: The crew of the ''Harekaze''. Atto mentioned in an interview the challenge of making sure each of the thirty-odd girls stand out visually from each other.
* ChekhovsGun:
** ''The cats''. [[spoiler:It's revealed that the ships that escaped being subverted all had cats onboard, which had hunted down the rodents spreading the HatePlague across the fleet.]]
** When Minami's observing a captured specimen, she notices that her digital wristwatch's display is on the fritz. [[spoiler:This is the secondary function to those damned rodents, after their primary function of mind control/triggering of hyper-aggression. When reinforcements for the flotilla of Toumai ships arrive, one of these vessels launches a salvo of Type-90 [=SSM=]s at the ''Aotsuki'', though not before we see several of those rodents were resting on the doors of the [=VLS=] before they were forced by the [=VLS=] doors opening to run for safety. This is followed shortly after by a major electronics failure aboard the lead instructor ship, and presumably all ships within a certain radius, before the anti-ship missiles cripple them.]]
* ChildhoodFriends: Akeno and Moeka whom both are become captains in their own respective ships. There is also Maron and Kuroki whom serve as the Harekaze's Engine Room.
* ClassRepresentative: The student crews are depicted as classes (the are all about the size of classes, 30 to 35 students and they even have a classroom on their ships) and the captain is depicted as the class rep in addition to being the captain (Misaki does the classic "Stand, bow, sit" in the first episode).
* CoolBoat:
** The series features the Battleship Yamato in a flashback, and the Musashi itself still in the series timeline as a training ship. The destroyer that Mike commands however is almost entirely fictional (the ''Harekaze''), although the ship class it is said to be part of is very real (the ''Kagerou'' class of destroyers) and although a real ship (of a different class) had a very similar, but not identical, name (''Harukaze'').
** There's also the ''Sarushima'', a modified ''Independence''-class Littoral Combat Ship.
** Episode two features the ''Deutchland''-class cruiser ''[[https://en.wikipedia.org/wiki/German_cruiser_Admiral_Graf_Spee Admiral Graf Spee]]'', flying the colors of Weimar Republic-era Germany.
* DavidVersusGoliath: Any battle that the ''Harekaze'' takes part in will essentially become this, as it's an undergunned and un-armored destroyer, and what's more, it's crewed by the lowest-scoring members of the freshman year.
** Kouko even says as much during the second episode, when the ''Harekaze'' goes up against the much larger ''Graf Spee'': a direct hit from even the cruiser's ''secondary'' guns would be enough to sink them. Their only advantage was the destroyer's speed and maneuverability, and they had to leverage those very carefully, as their 127mm gun wouldn't be able to hurt the cruiser back otherwise.
* DemotedToExtra: Moka. Features prominently in the pre-air advertising for the show, but come the telecast her significance drops substantially when its revealed that she's not even in the same ship as Mike. For most of the anime she plays no part, [[spoiler:and only shows up towards the finale.]]
* DoItYourselfThemeTune: All three members of [=TrySail=] (the trio that performs the opening theme) are part of the cast.
* DownerBeginning: In the second half of the first episode, [[spoiler:the ''Harekaze'' is fired upon by the ''Sarushima'' without warning, who ignores repeated radio calls trying to clarify the situation. This forces Mike to order the firing of a (unprimed) Long Lance torpedo to defend the ship. However because of the (dubious) damage sustained by the instructor's vessel, Mike and the crew of the ''Harekaze'' are branded as mutineers.]] What makes this even more impressive meta-wise was there was nothing in the promotional material that even pointed to this happening.
* DubInducedPlotHole: The CR translation, while mostly accurate, falls flat on its face when it comes to the terms used for the speeds the ''Harekaze'' is experiencing, due to the difference between how the [[https://en.wikipedia.org/wiki/Engine_order_telegraph Engine Order Telegraph]] was set up in Imperial Japanese Navy ships (like the ''Kagerou''-class the ''Harekaze'' was based on) compared to their contemporaries in the US Navy. This is further ''not'' helped by how the terminologies used by the two navies not matching up exactly. Suffice to say that when Mike says "full speed" most of the time it really ''isn't'' full speed.
* EnsignNewbie: Mike was assigned as the Captain, apparently by luck.
* AFatherToHisMen: Mike certainly thinks this way, where as the Captain of the ''Harekaze'' she is the "father", while all the girls under her command are her family. This means it's her responsibility to keep them safe [[spoiler:even if it means having to fire at the instructor's ship in self-defense.]]
* FlatWhat: The crew's reaction of Maron's suggestion of a festival in Episode, bonus for she's the one going to host it.
* FollowInMyFootsteps: The women of the Munetani family have all served in the Blue Mermaids since Mashiro's great-grandmother became the captain of its first ship. Mashiro, obviously, wants to continue the family legacy, which is why she enrolled at Yokosuka in the first place.
* ForeignCurseWord: Wilhelmina drops a "Scheisse!"[[note]]German for "shit"[[/note]]
* GenkiGirl: Maron and Coco.
* GirlsLoveStuffedAnimals: As episode 3 reveals, Mashiro loves stuffed toys. She accidentally brings a shark plushie to the bridge while she was half-asleep, and when Wilhelmina is assigned to be her roommate, its shown that her room is absolutely filled with all sorts of cute huggables which even the stoic German couldn't resist in giving a smile.
* GlowingEyesOfDoom: [[spoiler:Showed by the rodent that Tama was holding once the ''Harekaze'' was surrounded by the Blue Mermaid ships, and then on ''Tama herself'' once she goes berserk, as well as on every other infected character.]]
* HatePlague: [[spoiler:The reason for half of the training fleet going AWOL or aggressively attacking their compatriots.]]
* HiveMind: [[spoiler: Someone or something controls the HatePlague. This partially explains how otherwise inexperienced students in outdated ships capable of single handedly defeat groups of experienced Blue Mermaids in newer ships.]]
* ImprobableAimingSkills: Even with automation-assisted aiming, the shot that disabled the ''Graf Spee'' in episode two was ridiculously accurate, doubly so when one factors in the speeds each ship was moving at as well as the resistance the shell would encounter once it impacted the water.
* IdiosyncraticEpisodeNaming: Every episode's name includes the phrase "in a pinch" except episode 10 "Happy at the Equator Festival!" (which was a BreatherEpisode before the final big battle in the last two episodes), but including the two [=OVAs=].
* ImprobablyFemaleCast: Nearly all the named characters are either girls or women. While there ''are'' men shown, they're not part of the main cast.
* InSeriesNickname: "Mike" for Akeno, "Moka" for Moeka. This eventually follows to some of the Harekaze's crew, such as "Shiro" for Mashiro
* ItHasBeenAnHonor: In episode 12, as [[spoiler:''Harekaze'' sinks]], Mike salutes, followed by the rest of those present.

* LoadsAndLoadsOfCharacters: The crew of the ''Harekaze'' alone features around thirty girls (to put things in perspective, that's comparable to the entire Ooarai Senshado team in Anime/GirlsUndPanzer), and that's just ''one'' ship.
* LostInTranslation: In episode 4, the girls laugh at Wilhelmina's choice of using "washi" to refer to herself, as it's an archaic way of speaking more in line with old folk, and not a teenager like her. In the CR sub for the episode however, this was replaced instead with a lame reference to the dropping value of the Euro, which caused a LOT of confusion instead.
* MaleGaze: Several episodes give this for the sake of "Fanservice"
** Episode 1: Shows some of the Engineering Crew in their swimsuits.
** Episode 5, is a major cake due to a [[BeachEpisode beach episode]] theme. Another is a focus in Mike's midriff (her stomach) while showing a small part of her bra.
** Episode 6: During a conservation of the Military Higher-Ups (discussing [[BiggerIsBetter heavy guns size]], no less), the scene is [[DoesThisRemindYouOfAnything focused on Wilhelmina's chest]].
** Episode 7: During the raining scene (more swimsuits galore), a particular focus on Kaede as she clean herself nicely.
* MidSeasonUpgrade:
** The ''Harekaze'' swaps out its three [[https://en.wikipedia.org/wiki/12.7_cm/50_Type_3_naval_gun 12.7 cm/50 Type 3 naval gun turrets]] for [[https://en.wikipedia.org/wiki/10_cm/65_Type_98_naval_gun 10 cm/65 Type 98 naval guns]]. Historically the ''Kagerou-class'' were never refit for these during the war, instead relying on [[MoreDakka an increasing number of]] [[https://en.wikipedia.org/wiki/Type_96_25_mm_AT/AA_Gun Type 96 25mm guns]] for point defense and anti-air, but these guns were the default weapons of the ''Akizuki''-class of anti-air destroyers. Furthermore, the last surviving ''Kagerou-class'', the ''Yukikaze'', was re-fitted with the 10cm [=DP=] guns as part of her first post-war refit by the Taiwanese Navy, after she had been re-christened ''Tan Yang''.
** Due to battle damage sustained while fighting the ''Admiral Graf Spee'', those 10cm guns are replaced with [[https://en.wikipedia.org/wiki/5%22/54_caliber_Mark_16_gun 5"/54 Mk 16 naval guns]]. Originally designed as the secondary guns on the never-built ''Montana''-class of battleships, they first saw service as secondaries on the ''Midway''-class aircraft carriers. When the guns were later phased out, they were re-purposed as main batteries for various post-war JMSDF destroyers, such as the ''Murasame'' and ''Akizuki''-class destroyers.
* MildlyMilitary: The Blue Mermaids in general, and the crew of the ''Harekaze'', as a RagtagBunchofMisfits are no exception, being very lax even when they find themselves fugitives.
* MilitaryMoe: The show stars a naval training ship for high school girls.

** The first episode starts with two ChildhoodFriends reuniting to fulfill their childhood dreams, a class full of freshmen excited at their new assignment, and high school hijinks galore. It ends with [[spoiler:said class of freshmen having their ship ''fired upon with live ammunition'' by their instructor's ship for no discernible reason, then being branded as mutineers because they defended themselves.]]
** The BreatherEpisode 10 (an Equator Line-crossing festival) ends with all the girls [[CherubicChoir cheerfully singing a merry children song]]... which fades to [[spoiler:a [[CreepyChildrenSinging hollow echo of their voices]] and a shot of Captain Mike's worried face, alone on deck, as she ponders if the crew will be able to survive the mission that awaits them.]]
* MortalWoundReveal: After a full season of defying the odds, ''Harekaze'' returns to harbor. The crew disembarks, grateful to be on land once more, and it is a joyous moment... until [[spoiler:Harekaze begins to sink by the bow.]]
* NamesToRunAwayFromReallyFast:The [[spoiler:artificially created]] HatePlague is called the "Totalitarian Disease".
* TheNicknamer: Mike, though in her case she seems to do it to remember the names of her crew better. Incidentally, the nicknames she gives to her crew are popular nicknames for ''cats''.
* OminousFog: Something that is shown to surround the ''Musashi'' at the end of episode 4. Made doubly so when one remembers that there are no typhoons in the vicinity, and even the ''Harekaze'' has experienced nothing but clear weather since it left Yokosuka.
* PassingTheTorch: We have a straight example that acts as an InUniverse HeartwarmingMoment:

* PhenotypeStereotype: Wilhelmina, the German escapee from the ''Graf Spee''.
* PluckyGirl: This trope is in full force when it comes to [[http://www.lyrical-nonsense.com/lyrics/trysail/high-free-spirits/#page=English the lyrics]] for [[AnimeThemeSong the opening song]], "[[https://www.youtube.com/watch?v=LseERBatiSg High Free Spirits]]" -- especially these lines:
-->Sound out that definite determination as if it will never die out -\\
Leaving behind scars that will never be forgotten!
* RagtagBunchOfMisfits: The crew of the ''Harekaze'' seem to be this, as they've been described (by one of their own members no less!) to be the extra students of their year that didn't really fit anywhere else. Episode two reveals that only the girls that scored the lowest on the entrance exam are assigned to the ship. But subverted because Mashiro is one of the top students and that Kaburagi already earned a Doctorate degree [[spoiler:despite being [[TeenGenius only 12 years old]] ]].
* RealityEnsues: Turns out it's a bad idea to leave the Harekaze's interior and running lights on when trying to elude a hostile submarine at night. As stated by [[YouFool Wilhelmina]].
* ReasonableAuthorityFigure: Principal Munetani, as well as her daughter Mashimo. Not surprising, as Mashiro is on board the ''Harekaze'', and they obviously don't believe for a second that she'd mutiny.
* RedEyesTakeWarning: If their behavior wasn't enough of an indication of people infected with [[HatePlague Totalitarian Disease]], their eyes also glow red. Oddly, this effect isn't seen on victims at first when the plot wants to hide what's happening, but the eyes of the hamsters who spread it are red throughout the series.
* RefugeInAudacity:
** The only real way to describe how the ''Harekaze'' manages to disable the larger, better-armored, and MUCH more heavily-armed ''Graf Spee'' in episode two: that is, close in using the destroyer's speed and maneuverability to make a precision shot below the cruiser's water line to try and disable its propeller. As the bridge crew discusses before the plan is put into use, this is a LOT harder than it sounds, with an equal amount of things that could go wrong.
** Disabling the I-201 using the ''Harekaze's'' paravanes.
* RetiredBadass: Mayuki Munetani, the school principal and Mashiro's mother is a legend back in the day.
* RidiculouslyFastConstruction:
** The only way to explain how the crew of the ''Akashi'' manage to replace the 12.7 cm guns of the ''Harekaze'' with the 10cm twin high-angle guns within a day, instead of the ''days'' it would have taken in the real world[[labelnote:Explanation]]In the real world, many of the ''Kagerou-class'' never survived long enough to be refitted with the latter weapon, and even the ''Yukikaze'' made do with an increasing number of 25mm guns to aid in its anti-air defense, until it was re-fitted with the 10cm twin [=DP=] guns after the war while in the hands of the Taiwanese. While specs-wise the 10cm gun could ''theoretically'' fit in the turret ring of the 12.7cm guns used by the ''Kagerou''-class, it was ''not'' an exact fit, and would require extensive modifications to ensure it functioned properly.[[/labelnote]].
** New levels of ludicrousy are reached when those 10cm guns are replaced with US-made 5"/54 single [=DP=] guns. The ''Kagerou-class'' was never designed to accept American armaments.
* RuleOfCool: While the show tries to make the naval engagements appear plausible based on the actual mechanics of the ships involved, there are also some situations where things just happen because the production staff thought it was cool.
** Is there any real reason for Noma Machiko (the ship's lookout) to make her flag signals ''on the spar of the ship while it was under fire'' aside from this?
** The combat distances portrayed are also much ''much'' more closer than the actual ranges mentioned by Mike and her bridge crew, as well as the amount of time required for the ships to perform said combat maneuvers.
** Again, disabling the I-201 using the ''Harekaze's'' paravanes. While based on [[http://i.imgur.com/dcvbR57.jpg a very real tactic used by destroyers against subs]], using the paravanes to foul up the sub's propeller would have been extremely dangerous had it been done in the real life for both ships, and this isn't even taking the depth charge into consideration yet.
** Tama getting swept back onto the deck of the ''Harekaze'' after Wilhelmina throws her overboard. While getting swept back on-deck IS possible, in real life it would ''also'' require gale-force winds, and the ship was shown to be on calm seas when it happened.
** The ''Harekaze'' intercepting the Musashi's incoming shells with its own ordnance. While this ''has'' happened before in other media (see Manga/{{Zipang}}), ''unlike'' what happened with the ''Mirai'' (which had very modern targeting computers, a superb air search radar and the Aegis Combat System guiding its missiles), the ''Harekaze's'' interception came down Tama ''computing the angle of the shells, their average flight time, as well as their velocity on the spot'', not to mention the adjusting the elevation of the ''Harekaze's'' own high-angle guns so its own shells would strike the battleship's shells head-on.
** Generally speaking, most of the older ships have a much faster fire rate than they ought to. For instance, the main guns of Musashi could actually only fire about once a minute, because it took that long to reload them. And that with a crew of 50 or 100 per turret; the student force on Musashi would have been far smaller.
* RuleOfThree: Played straight [[spoiler:and then subverted in a meta level]] with the Harekaze crew status reports to the bridge, with two being serious from Artillery or Engineering, and the third one being from kitchen staff reporting something trivial.
** First example in episode 1: under attack by [[spoiler:Sarushima]], Engineering reports water in boiler room, Artillery reports damage in the autoloader, Kitchen reports the rice cooker is broken.
** Second example in episode 11: to make Captain Mike know they are willing to fight, Artillery reports being ready and asks for targets, Engineering asks which speed does the Captain need, and Kitchen reports they made rice balls.
** In episode 12, [[spoiler:what would be [[InvertedTrope a third, expected usage]] is ''very conspicuously'' averted: as Musashi is bombarding the Harekaze with guns ''[[{{BFG}} so big]]'' that even [[RealityEnsues not-so-near misses could sink the ship]], [[SubvertedTrope every single report]] is deadly serious and there aren't just three of them.]]
* SadisticChoice: At the start of episode 3, Mike is forced to decide between coming to her friend Moka's aid in the wake of a panicked distress call from the ''Musashi'', or turning back and heading to their home port, where there's a good chance that she and her crew might be arrested and tried for mutiny. [[spoiler:Mike eventually settles for the latter, as Mashiro points out that there's probably little good that the ''Harekaze'' could even do in its current condition (running out of supplies and ammunition, and its engine damaged enough that it could only go slightly faster than its cruising speed), and what's more if the ''Musashi'' turned out to be hostile, their destroyer wouldn't be able to defend itself anymore.]]
* SequelHook:
** [[spoiler: After the ending, there is still not much information about TheVirus, as in who made it, for what purpose, and who or what is controlling its HiveMind]].
** [[spoiler:Harekaze sinking]] while docked at harbor can be easily [[spoiler:refloated]] if story demands it.
*** [[spoiler: As it turns out, they get a new Kagerou-class destroyer, the Okikaze. Much is made of how she's identical to the original Harekaze, she's fitted with salvaged parts from the original Harekaze, and she is, in the end, renamed the Harekaze.]]

** In episode two, the Engineering Crew complains to Mike about having the ''Harekaze'' run faster than its regular cruising speed (just a little under 33 kmph). In RealLife UsefulNotes/WorldWarII destroyer captains avoided doing so unless it was direst of emergencies, and with good reason: the steam pressure that was needed to even maintain that sort of movement was simply not sustainable, and increased the chance of a catastrophic engine breakdown (read:explosions).
** The Harekaze's depth charge not sinking the I-201 outright, and instead forcing it to surface. Despite what action movies tell you, [[RealityIsUnrealistic historically fewer submarines were lost due to direct depth charge damage]]. This is due to how [[https://en.wikipedia.org/wiki/Depth_charge#Underwater_explosions depth charges worked]], and as the anime showed, the detonation of the charge was nowhere within the "kill" radius (less than five meters) required to sink the sub. However it was still within the radius to ''disable'' the sub (either by crew or subsystem damage), which would almost always force the sub to surface.
** ''Hiei'' is initially mistaken for a Yamato-class at a distance. ''Hiei'' had a unique superstructure among the Kongo-class battleships, used to prototype for the Yamato-class ships. Realizing a moment later that the ship has twin turrets instead of triple turrets allows the correct identification.
** Tying in with the example above, mistakenly identifying a ship's type, and thus its size, can lead to grossly incorrect distance to an object when using optical calculations.
** In Episode 9, Wilhelmina points out that the ''Graf Spee'' has a critical weakness in that it has an important steam pipe exposed above the deck, and a hit on this pipe could completely disable the entire ship. This was an actual design flaw in the ''Graf Spee''.
** The 'Crossing the Equator festival' is a real world navy tradition in almost every fleet, both in World War II and today.
** Even Harekaze's name is a case of shown their work, for it matches Japanese Warship Naming Conventions from WWII, which started that 1st Class Destroyers, which were destroyers that displaced more than 1,000 tons were named after natural phenomenon, often some type of wind, hence the frequent occurance of "kaze" in destroyer names, in this case Harekaze means Sunny Wind.
* SpeaksInShoutOuts: Done by ship doctor Minami Kaburagi. She seems to have a fondness for Chinese proverbs or idioms:
** In episode 2, she references '''The Analects of Confucius''' (Book IX, section 28).
** In episode 3, she quotes Chūn Xiǎo (translated as "Spring Dawn"), a poem by Tang-dynasty poet Meng Haoran.
* SyntheticPlague: According to the 8th episode, the virus (and possibly [[spoiler:the rodents]] spreading it) were artificially created [[spoiler:on a lab submarine]], that had an accident.
* TerseTalker: Shima Tateishi.
* ThemeMusicPowerUp: The full version of the opening theme plays when [[spoiler: the Harakaze rams into the Musashi.]]

** Much like Anime/GirlsUndPanzer, the surnames of the ''Harekaze's'' crew are references to someone or something, usually by section.

** The Captain's nicknames for her officers (including herself) are traditional cat names in Japanese.

* TheStoic: Tama and Kaburagi.
* TwoKeyedLock: The ''Harekaze'' features this -- Mike and Mashiro have to use the keys given to them to unlock the systems that allow the ship's autoloader to use live ammunition for its 127mm gun.
* UnfriendlyFire: The ''Aotsuki'' is gutted with a salvo anti-ship missiles launched by the ships that were supposed to be reinforcing them, due to the crew on the reinforcing ships being mind-controlled.
* WhatTheHellHero: Mike goes in away missions quite often. Worst offender is she doing it in the middle of a battle to try and save Moka in a way that qualifies as ''abandoning'' her ship and crew - to clarify, she ''does'' hand command to her first officer, but her hurry and preocupation for her friend makes her do it in a rather informal way, without making sure the chain of command remains intact. Mashiro calls out Mike on her behavior on that (and other) situations, reminding her that a Captain always needs to prioritize their own crew's safety. [[spoiler:Mashiro's scolding eventually works: whenever Mike goes in ''more'' away missions afterwards (now, only when her personal skills are needed), she takes care of formally transfering command and laying precise instructions.]]
* YoungerThanTheyLook: [[spoiler: Minami Kaburagi, the ship doctor]] is only 12 years old.

* ClassroomRepresentative: The student crews are depicted as classes (the are all about the size of classes, 30 to 35 students and they even have a classroom on their ships) and the captain is depicted as the class rep in addition to being the captain (Misaki does the classic "Stand, bow, sit" in the first episode).

** Meanwhile, the cats are named for WWII Japanese admirals; Isoroku for Isoroku Yamamoto (which makes Mike's joke about making him a vice-admiral a ShoutOut, since that was Yamamoto's actual rank) and Tamonmaru for Tamon Yamaguchi.

* IdiosyncraticEpisodeNaming: Every episode's name includes the phrase "in a pinch" except episode 10 "Happy at the Equator Festival!", but including the two [=OVAs=].

** Meanwhile, the cats are named for WWII Japanese admirals; Isoroku for Isoroku Yamamoto and Tamonmaru for Tamon Yamaguchi.

** New levels of ludicrousy are reached when those 10cm guns are replaced with US-made 5"/54 single [=DP=] guns. The ''Kagerou-class'' was ever designed to accept American armaments.

** Even Harekaze's name is a case of shown their work, for it matches Japanese Warship Naming Conventions from WWII, which started that 1st Class Destroyers, which were destroyers that displaced more than 1,000 tons were named after natural phenomenon, in this case Harekaze means Sunny Wind.

* IdiosyncraticEpisodeNaming: Every episode's name includes the phrase "in a pinch".

** In episode two, the Engineering Crew complains to Mike about having the ''Harekaze'' run faster than its regular cruising speed (just a little under 33 kmph). In RealLife WorldWarTwo destroyer captains avoided doing so unless it was direst of emergencies, and with good reason: the steam pressure that was needed to even maintain that sort of movement was simply not sustainable, and increased the chance of a catastrophic engine breakdown (read:explosions).

* [[spoiler:SyntheticPlague]] According to the 8th episode, the virus (and possibly the [[spoiler:rodents spreading it]]) was [[spoiler:artificially created on a lab submarine, that had an accident.]]

* ThemeNaming: Much like Anime/GirlsUndPanzer, the surnames of the ''Harekaze's'' crew are references to someone or something, usually by section.

** Ironically the secondary armament of the ''Graf Spee'' is likely more dangerous to the ''Harekaze'' than its main guns. Designed to deliver a devastating punch to heavily-armored cruisers and battleships, the armor-piercing rounds of the main battery would likely punch right through the unarmored ''Harekaze'' without exploding. The big-gunned ships just aren't designed to fight something as puny as a destroyer and, historically, [[https://en.wikipedia.org/wiki/Battle_off_Samar tend to have a lot of trouble when forced to do so.]]
* DemotedToExtra: [[spoiler:''Moka''. Features prominently in the pre-air advertising for the show, but come the telecast her significance drops substantially when its revealed that she's not even in the same ship as Mike. It's still early in the show's broadcast life however, so there is still a chance that she'll play an important role again.]]

* NiceJobFixingItVillain: The ''Graf Spee'' attacking the Wilhelmina, and later on Mike when she tried to rescue the former, actually helped the ''Harekaze'', since its secondaries -- which were the only armaments fast enough to track the destroyer as it made its attack run -- were fixated on targeting Mike instead. As a result the ''Harekaze'' was able to land its crippling blow to the cruiser's engines.

* [[CrewOfOne Improbable Crew Size]]: All the Blue Mermaids' vessels, from the smallest of destroyers to the largest of battleships, are crewed by thirty people. While extensive automation makes this plausible for something as small as a ''Kagerou''-class destroyer, the explanation starts to crack a bit for larger ships like a ''Takao''-class heavy cruiser, and completely falls apart for something as big as a ''Deutschland''-class battlecruiser, or even a '''''Yamato'''''-class super-battleship.

* ChangingOfTheGuard / PassingTheTorch: PlayedWith a lot, a it's at the same discussed, invoked, ''very'' downplayed, and a key plot point for most of the series, '''plus''' it's played straight for a ''different'' plot point at the end.
** For most of the series, Mike has a tendency to go on [[TheMainCharactersDoEverything away missions]] at the drop of a hat, leaving Mashiro in charge in a ''very'' informal way and often without giving precise instructions ([[{{Understatement}} something that's not exactly good for the chain of command]]) instead of performing a proper, ''literal'' ChangingOfTheGuard. An exasperated Mashiro [[DiscussedTrope calls her on that quite often]], culminating with a WhatTheHellHero speech after a particularly egretious example. Near the series' end, [[InvokedTrope when it becomes necessary for Mike to transfer command again]], she does a fully formal transfer of command, complete with [[PassingTheTorch Passing the Captain's Hat]] for Mashiro's first mission as Captain. Downplayed, as the transfer lasts only half an episode.
** And then we have a straight example that acts as an InUniverse HeartwarmingMoment:
--->'''Mayufu Munetani:''' Sorry, Mother, it seems you missed your chance to write history again.
--->'''Mayuki Munetani:''' It's fine. My students did in my stead.

--->'''Kouko:''' ''[looking at the birds flying by]'' At times like this, I wish we could fly back to school like that. ''[turning to Mashiro]'' I wonder if you can make a flying ship without hydrogen or helium?\\

** The default armament of the ''Independence''-class LCS is a [[https://en.wikipedia.org/wiki/Bofors_57_mm_gun Bofors mark 110 57mm gun]]. This was accurately shown for the first half of episode one. However by the second half, it seemed to have spontaneously morphed into a [[https://en.wikipedia.org/wiki/5%22/54_caliber_Mark_45_gun 127mm/L62 Mk 45 Mod 4]], which is the standard weapon of the ''Atago''-class of guided missile destroyers used by the real-world JMSDF. The rate of fire it showed (an almost casual 20 rounds-per-minute) [[spoiler:when it attacked the ''Harekaze'']] also matched up with the Mk 45, as a Bofors 57mm would have instead put out a blistering ''200+ rounds per minute''. In addition, the LCS is shown having its standard flight deck for helicopters and [[https://en.wikipedia.org/wiki/RIM-116_Rolling_Airframe_Missile SeaRAM point defense missiles]] above the helo hangar, even though it's explicitly stated that heavier-than-air flight does not exist in this universe.
*** Episode 7 throws this and the ''Akizuki''s supposed lack of reason for existence in for a loop due to the appearance of an airship.

** Except in the "Sumo" match, Maron rigged the match for Kuro-chan.
* BornUnlucky: Mashiro seems to think that she's this. She gives the Fusou sisters from VideoGame/KantaiCollection a run for the money with how much she repeats how unfortunate she is.
* BreatherEpisode: Episode 4. There's no big battle, and most of it is spent on the crew just relaxing for a change, while Mike takes an away crew to a ocean-based shopping mall to acquire supplies.

* CoolBoat: The series features the Battleship Yamato in a flashback, and the Musashi itself still in the series timeline as a training ship. The destroyer that Mike commands however is almost entirely fictional (the ''Harekaze''), although the ship class it is said to be part of is very real (the ''Kagerou'' class of destroyers) and although a real ship (of a different class) had a very similar, but not identical, name (''Harukaze'').

*** Ironically the secondary armament of the ''Graf Spee'' is likely more dangerous to the ''Harekaze'' than its main guns. Designed to deliver a devastating punch to heavily-armored cruisers and battleships, the armor-piercing rounds of the main battery would likely punch right through the unarmored ''Harekaze'' without exploding. The big-gunned ships just aren't designed to fight something as puny as a destroyer and, historically, [[https://en.wikipedia.org/wiki/Battle_off_Samar tend to have a lot of trouble when forced to do so.]]

* GlowingEyesOfDoom: [[spoiler:Showed by the rodent that Tama was holding once the ''Harekaze'' was surrounded by the Blue Mermaid ships, and then on ''Tama herself'' once she goes berserk.]]
** [[spoiler:Anyone who is infected had this as well.]]

* AluminiumChristmasTrees: Mashiro's shark hug toy is a real toy by IKEA. There are even some branches that [[http://www.ikea.com/hk/en/catalog/products/60298026/ still have it in stock]].

** Episode 6: During a conservation of the Military Higher-Ups, the scene is focused on Wilhelmina's chest.

* HatePlague: [[spoiler:What SEEMS to be the reason for half of the training fleet going AWOL or aggressively attacking their compatriots, as displayed when Tama goes absolutely ''nuts'' when the ''Harekaze'' gets surrounded. It seems to be spread via rodents.]]
** Confirmed in Episode 6 as stated by Minami.

** The BreatherEpisode 10 (an Equator Line-crossing festival) ends with all the girls [[CherubicChoir cheerfully singing a merry children song]]... which fades to [[spoiler:a [[CreepyChildrenSinging hollow echo of their voices]] and a shot of Captain Mike's worried face, alone on deck, as she ''literally'' ponders if the crew will be able to survive the mission that awaits them.]]

Akeno Misaki, nicknamed "Mike", is one of these hopefuls, and enrolls in the prestigious Yokosuka Girl's Marine High School in the hope of one day joining its ranks. There she meets up again with her ChildhoodFriend Moeka China, who is now the captain of the training ship Musashi. Moeka would also want to one day join the Blue Mermaids, so who among the two friends will reach their dream first?

'''High School Fleet''' (ハイスクール・フリート), also known as '''Hai-Furi!''' (はいふり), is an AnimeFirst series by Creator/ProductionIMS that premiered during the Spring2016Anime season. It features character designs by Atto (of Manga/NonNonBiyori fame), as well as many of the staff that were part of Anime/GirlsUndPanzer's production.

!!Hai-Furi features the following Tropes:

* {{A-cup Angst}}: In episode 6, some of the girls in the Engineering Dept react badly as they see Wilhelmina's [[https://media.giphy.com/media/trq4NCEbDsW3K/giphy.gif larger assets]].