Guess Reiji's not the only one who can potentially instill the omnicidal killbot mode in shipgirls, Bismarck's admiral probably can... though the sight of a sadistic Bismarck scares me.

According to the artist commentary, a bit of backstory about this admiral is in the artbook that came out in C91. So I went and checked it again, and looks like he used to serve in the Marines.
Also, almost to the end of the book was a status report of all members of Reiji's former unit after their last operation, along with this pic; and of course, out of 32 platoon members all but Reiji was KIA. Two of the names listed got my attention: