Gedou Majutsushi no Hyouitan: Saikyou Kenshi wo Nottottara, Jibun no Karada wo Sagasu Koto ni Natta

"It's about time I change bodies." A magician who lived for hundreds of years by taking over people's bodies was taking a stroll through the forest in search of a new vessel, when he found a young man who was on the verge of dying with a great number of slaughtered monsters before him. With the condition that the magician would protect Erena, the man's companion, the man let the magician take his body. However, what the magician did not know was that the man was the swordsman who had been expelled from the hero's party.

(Source: Shousetsuka ni Narou, translated)