More specifically, the anime kind of tosses out a ton of the plot to to focus upon more laser battles between Kongou and Iona.
For example, in the anime, the main cast in the I-401 defeat Haruna and Kirishima alone, then Haruna meets Makie and their plot basically ends as soon as the raid on the mansion is over and they just hop onboard the I-401 that just waited around for them for absolutely no reason so that basically all the important characters are all onboard the same boat.
In the manga, the Japanese government built a human-made submarine meant to take on the Fog called the White Whale, and it has an entire secondary cast of characters onboard, including the former sonar operator of I-401 who quit because she had a crush on the male lead and he was obviously never going to return it, and the White Whale then goes off on its own separate adventures. Haruna takes Makie up to meet her "brother", another design child that runs Hokkaido and they get engaged in the politics of the Japanese government, letting Haruna be an audience surrogate who needs to understand how politics work in this time period. In fact, it's probably notable that Iona and the main cast don't even show up in some volumes of the manga, the manga has so many different balls in the air.
It's understandable why the anime decided to zero in and focus on the main cast rather than the at times ridiculously meandering political stuff and the tremendous secondary and tertiary cast, but it also winds up making things boring when it basically becomes a monster of the week deal where they always solve all their problems by just shooting their wave motion gun giant frikkin' laser beam at the next ship they come across.
Plus, you won't see School Uniform Takao, Haruna, or Kirishima in the Ars Nova continuity, much less Akagi, Akashi, sane Kongou, or I-400 and I-402 as independent entities.
Heck, you won't get to see a lot of the backgrounds of anyone who isn't Iona.
Seriously, normally dressed Kongou without the obsession she's carried through the last few story arcs is surprisingly hot. See chapter 90 for what I mean.
There may be an entire army of them considering how many hatches there were.
WHY DID SHE MAKE THEM!?
To move stuff, apparently.
I came here because I heard you had Kaga books!Eh!?Shut up, it's a pure coincidental resemblance!Akagi! It's enough,
no matter how you look at it, it is a Kaga book!Wah♥ Waha♥
Is that you, Kongou?How nice! It suits you♥
Circle Chihaya Musashi
End of Line
Thank you very muuuch.Okay! I got to see something nice, so I'll be expecting it next time!