WMG / Arpeggio of Blue Steel

Not the real Shouzo Chihaya
The guy seen at the head of the Scarlet fleet is not really Gunzou's dad. We know that Mental Models can create nanite clones of people. Heck, Iona did it and she's a scout sub turned attack sub. Musahi being a flasghip would have more processing power and be capable of creating a more advanced lifelike model. Later, we may find out the real Shouzou Chihaya died a long time ago. Musashi's simply using using him for psychological fear factor. He was a well respected commander after all.
  • Confirmed in the Ars Nova series, still up in the air for the manga.

Potential for New Characters
Who could show up next? We've seen the Lexington, which opens the way for such possible new characters as the Iowa, or any of the other famous American vessels of that time. Alternatively, we may see the Design A-150, otherwise known as the cancelled project for the Super Yamato Class.
  • Since the Fog seem to have emulated the entire battle fleets of World War II, we've only seen a fraction of the ships just patrolling Asia.
    • The fourth Takao class sister Chokai and Yamato's half-sister Shinano are conspicuous in their absence from the story so far, given how much attention their sisters get. Presumably Chokai is part of Nagato's fleet and Shinano is moored with the other Asia Fleet carriers. For that matter, we've barely met anyone from Nagato's fleet, which is half of the ships around Japan.
    • It's probably only a matter of time before Prince of Wales gets a proper introduction. Her desire to hunt down Repulse is still unresolved.
    • That said, however...

The Bespectacled Mental Model in Chapter 79 is actually Shinano.

  • In one of the pages during Yamato's monologue, there was a separate scene of the said character beside what was revealed to be a life pod containing Gunzou Chihaya. In connection, Yamato was communicating to her in the previous chapter via mental link, regarding a future plan involving the Fog Fleet and possibly Gunzou.
    • Conversely, it could be Chokai, since she looks a lot like Maya when she takes her glasses off.
    • Jossed. Chapter 80 reveals her identity as Choukai, while Shinano could possibly be one of the two new characters introduced in the splash page.

The Fleet of Fog's Origins
  • Ancient weapons from an ancient human star spanning empire
    • Which was actually the human empire from Halo also making this a crossover. The Fog are AIs that have become rampant with age and lost track of their original mission of hiding until the Forerunner were gone and then helping humanity rebuild. The "Admiralty Code" is an undegraded copy of their original programming as laid down by the Lord of Admirals that could be used to repair them. They don't really known this, but they somehow know it's important.
  • The Enemy Without.
  • A type of False Flag Operation. The Fleet menaces the world for a while, then their creator "develops" a system to counter/destroy them, gaining power and influence in the process.

FOG Girls Academy is one of the premier private schools in the country. Unfortunately, they're short on money and can't stay open unless they amalgamate with two local schools; Yokosuka Technical School and Yokosuka Middle School. Thus begins the mixing of three student bodies...
  • Gunzou, Sou, Kyouhei and Iori are all from Yokosuka Technical School (pretty much exactly as they are in the source material). Shizuka is a recent transfer.
  • Iona, I-400, and I-402 will be triplets infamous for trolling other students and getting trolled by Kotono in turn.
  • Kongo will be the Alpha Bitch former Student Council President who's given up the job to Hiei so she can enjoy her final year at the academy without any real responsibility. Still has an unbreakable reputation as "The Iron Lady" to overcome.
  • Takao will be Exactly the same.
  • Atago will be Takao's nearly-identical little sister while Maya is a cousin and sister to Chokai.
  • Hyuuga will be a chemistry Sensei-chan. That way we can have Lab Explosion shenanigans. Education Through Pyrotechnics for the win!
  • Kotono (alive and well) will be the Spoiled Sweet Most Popular Girl In School. May or may not be a Mafia Princess for comedy.
    • "Yamato Amaha" will be the Principal of FOG Academy. Everyone notes the uncanny resemblance between herself and her daughter, Kotono.
  • Musashi will be Yamato's sister, with the same traits.
  • Nagato will be Twins of the same name. One of them is a teacher, the other runs a flower shop. Persistent rumor claims they switch places...
  • Hiei will clearly be student council president (mostly because Kongo didn't want the job).
    • Myoukou, Nachi, Ashigara and Haguro are Student Reps of their respective grades on the council.
  • U-2501 will be a foreign transfer student from Germany.
  • Zordan is a strict but honorable teacher. German, of course.
  • Makie is a child genius who's skipped a few grades, winds up in the same class as Haruna and Kirishima.
  • Haruna is a painfully shy girl in Makie's class. She is into cosplay and is member of Sewing Club. Carries a Thesaurus around everywhere. Nobody's sure how she fits that giant coat into her school bag.
  • Kirishima is Haruna's best friend and Hot-Blooded athlete. Surprisingly good at puppetry, her "dancing teddy bear" routine is very popular with younger students like Makie.
  • Daisaku Komaki is a teacher and Maruri Hibiki is the teaching assistant he has the not-at-all-subtle crush on.
  • Mitsumine, Kita, Kamikage, etc. would all be members of the school board, possibly Shouzou Chihaya as well.
  • Gunzou's mom is exactly the same (right down to being covered in birds half the time). Chances are she and Shouzou are still together. He's retired from the navy and writes Tom Clancy style doorstoppers.

You are all free to add to this...

Fantasy Cast for the English Dub

While any dub is a long shot, considering the niche appeal of Arpeggio, we can still dream right?

Everyone is free to express their thoughts.

Gunzo's mom is behind the Fog
Why? To set up her little boy as a Harem Protagonist of course! Why? Because She Wants Grandkids.
  • She is indeed training Takao to be a bride.

Takao will return in the anime.
Since Maya in the anime is just a basic AI, that leaves us with a fully-functional Takao-class Fog heavy cruiser just waiting to be moved into.
  • Yes and no. Maya's ship body is absorbed by Kongou in the series climax but Takao gets a new ship for the Cadenza movie.

Kongou will pull a Heel–Face Turn
...or at least a Heel-Neutral Turn, due to her considering the current situation as an Enemy Mine.
  • No. Blue Steel handled 400 and 402 on its own.
    • Yes, she did after all.
  • She could still come back in the Cadenza movie as a surprise ally against Hiei. Bonus points if she plays Maya's piano.
    • Confirmed as 11th hour ally in Cadenza.

I-400 and I-402 lied to Kongou about Maya
I'm copying this fan-theory from an acquaintance of mine, so as you know:

"Watching and rewatching the anime... I don't know. I get the feeling that 400 and 402 LIED to Kongo. Rather they waited for Kongo to be preoccupied with 401 and then shut down Maya's Mental Model and swapped it out for a dummy program. It's a cold blooded, calculating move but Maya's behaviors prior are simply too complex to replicate by AIs who have no comprehension of emotion.

Maya expresses hate at Takao for blocking her attack. She is able to EXPLAIN an emotional concept to 401 (In a childlike manner but still...) to Iona. She exhibits enthusiasm. play, curiosity. All to fool Kongo? Not too likely.

Consider: They believe that Kongo may be tainted. IF (for sake of argument) Maya had a true Mental Model as well, that would also be likely be true of Maya also. it is safer to deal with Maya first and cut out Kongo's most loyal subordinate rather than try to deal with Kongo AND Maya at the same time.

It is reasonable to hope that somewhere awaiting discovery is Maya's real core."

What do you all think?

Nagara's Core is wandering around on her own.
While it's been established that light cruisers like Nagara aren't capable of generating a Mental Model and maintain their ship body, what if the ship is sunk but the core's still intact? Rather than being recovered by a yet-unknown party, Nagara could have just walked away of her own volition and not told anyone.

Haruna will use her coat to partially restore Kirishima's body
Now that Haruna's entering the Yokosuka school to investigate the Facility 4 fire, she'll not be wearing her signature overcoat (against uniform rules and all that). Rather than letting all that nanomaterial go to waste sitting around, she could give it to Kirishima to rebuild her body. There's not enough for a full restoration but probably enough for Kirishima to stand about Makie's height and pose as her best friend or sister while Haruna's away.
  • Possibly confirmed: a splash page for Chapter 80 includes a reconstituted Kirishima in a child-like body. Yet to be confirmed in the comic itself.

Russian ships Mental Models will be male
The Russians use male pronouns rather than female ones for their vessels so it would be fitting to have russian ships to have boys as their mental models.

    Jossed Theories 
The Fog use the sunken wrecks of WWII Era ships.
This is a bit of Fanon that has stuck around, especially for American Fans, since the beginning, and it's beginning to become a problem regarding the accuracy of the application of Tropes.

While true most of the historical Japanese navy was sunk by war's end, and are now at the bottom of the sea, many ships that are featured in the series, such as Haruna and Hyuuga, were raised and/or scrapped after the war. This suggests that whatever the Fog are, they don't require a physical wreck to repair and improve on in order to form their ships. This means that things such as the great multitudes of Nagara-Class cruisers in the anime (historically only numbering in 6 ships), is a hint at the Fog's true nature.

Yamato will appear in the anime.
At the end of Episode 7 of the Anime, Kongo has had enough of Gunzo's shenanigans with the Fog and has ordered a full assault on Iwo Jima. As this is a 12 episode anime, that means the endgame has begun, and more likely that not will end on a cliff hanger with I-401 and Blue Steel sailing into the sunset for the US.

Granted, the anime was well off the rails by episode 6, but if the studio wants to prevent any second season from becoming In-Name-Only, they will need to follow what comes next in Broad Strokes if nothing else, and chances are that means Kongo will most likely become demoted from the Big Bad to The Dragon to none other than Yamato.

The ideal way, as can be assumed at this time, to do so would be to model to reveal on Azula's from the end of Book One: Kongo, damaged and defeated, limps to the massive Yamato (or meets her in her little tea garden chat room), kneels and requests backup. Without a word, Yamato steps out of the shadows with a grim smile.

A long shot, but it would be awesome.
  • Nope. The anime ends with the I-401 finally reaching he US and delivering the Vibration Torpedo.

The maid we see serving Saori Chihaya in chapter 48 is Nagara's Mental Model.
I-400 and 402 has been searching for the core of Nagara for months with no avail. The maid also used some rather peculiar way to address herself. It is, therefore, not a great stretch that she is either a gynoid akin to Osakabe's maids or the mental model of Nagara.
  • Jossed by Book 8. She is a human, and Nagara's core is retrieved by unknown parties before it developed one.