Arpeggio of Blue Steel (Aoki Hagane no Arpeggio) was a fairly succesful anime in fall of 2013. The setting is familiar to anyone who has read or watched a few futuristic action animes or mangas. In the not too distant future the world’s sea levels have risen considerably, changing the current landscape. The twist here is that humanity is effectively blockaded by the mysterious and powerful Fleet of Fog, which appears to be made up of modernized World War 2 warships. Travel between landmasses by air or sea is impossible. A Submarine, I-401, has mysteriously shown up at a Japanese port. (the real I-401 is quite an interesting ship, btw) The subs AI, which has the ability to take a human form called a mental model, decides to take on a small crew and a captain and then goes rogue. She chooses Gunzou Chihaya, the son of the admiral who commanded the UN naval fleet that opposed the Fog when they first appeared.
The manga is very good. In my opinion, it is superior to the anime, which diverged from the original story early. The manga is worth checking out even if you watched and enjoyed the anime. Intrigue and action are the basic core of Arpeggio, but it also explores shifting allegiances and what it means to be human. There are a number of connections between Chihaya and the Fleet of Fog, which builds a nice mystery. Since who is on who’s side is fluid, the reader is left to wonder what will happen in any given encounter. The only thing that I would consider a drawback is that there are a large number of ships in the Fleet of Fog, and it gets challenging to keep them all straight. The manga is available on Crunchyroll’s manga service and in print form from Seven Seas Entertainment. It is released monthly with 61 chapters currently available.