A Certain Man Thrice Out Of Time (Marvel/DC/ToAru SI)

Sometime after a feather struck his mind, Touma Kamijou had regained memories of a past life. A past that had been riddled with heroism fit for legends. A past life that did not belong to the current world he lives in. Now, the Captain had awakened, and with the children of magic and science having suffered enough, it was time for him to get to work.