hi komi, and welcome to Subsim.
Man, don't I wish there was a Silent Hunter IJN version. The closest I can think of is SH4, where you play as an American submariner fighting the IJN. So, you see and interact with the IJN, but alas, you cannot play as a Japanese. Maybe there is a mod that someone can recommend that puts a playable IJN sub in the game?
One day I will be retired, and this would make a great mod/crowd funded project, yeah? I just don't have the time currently but I would love a "Japanese Aces" game.