I emailed SubCommittee member Kanji (who lives in Japan) about this movie. Here is his reply...
All I heard about this movie is that it is story about fiction Type I (I-gou) sub going to solo attack to Tenian to prevent 2nd Atom bomb. It carries "Lorelei system" which is secret scanning device. .. And rest of the story is totally Sci-Fi or Japanese animation like. If you expect serious sub movie like Das Boot, this one is not for you. And digital SFX is totally out of date. I will watch it when DVD is released, though. . .