Arpeggio of Blue Steel (Takao x Male Reader)

Y/N, a good friend Chihaya Gunzo from Marine Technical Academy and a Captain. He knows that Chihaya captains a Fog ship a WW2 Japanese submarine I-401 aka Iona battling against the Fog using WW2 ships and mental models, that looks like humans but very powerful and dangerous. Y/N plans getting a ship like Chihaya and have a relationship with a girl. One night, he stumbled upon a gorgeous girl with blue hair at a book store in New Hakodate City, Hokkaido. She was get picked off by couple of dudes.
What future holds for Y/N?
(Fanfiction Don't own the anime)