MUGEN NO GUNKAN YAMATO

Mugen no Gunkan Yamato summary:

Kamihara Kurusu who lost his consciousness found his soul in a time slip to Showa 16 (1941), the day battleship Yamato is launched. After realizing his situation, Kurusu sets out on a game to make Imperial Japan win the Pacific War. With the help of an ensign who can see and hear him, he shared his knowledge about the history of Pacific War to Yamamoto Isoroku, commander of the combined fleet. But in this game, his opponent is not just the United States, it's the force of history itself.