There's a hopelessly unlucky battleship captain who can do the splits in midair. One day, he botched a split, hit his head, and transmigrated.
In the Demon Slayer world, he inherits Yae Sakura's abilities from the start. How awesome is that?
Serious summary: After more than ten years of being dazed and foolish, he suddenly comes to his senses. It turns out he's the battleship captain who does the splits in midair, there's a Hyperion in his mind, and he can inherit the powers of the Valkyries.
Wouldn't it be great to wield Yae Sakura's swordsmanship and dominate the Demon Slayer world?
P.S.: I originally wanted him to transform into Yae Sakura in Demon Slayer, but I thought better of it.
Also, Shinobu Kocho, Kanae, and Yae Sakura are all my wives!
We're all adults, so of course we don't have to choose just one!