Arafoo Kenja no Isekai Seikatsu Nikki

Forty-year-old Satoshi Osako is a farmer in the Japanese countryside—and a hardcore player of Swords & Sorceries, an online VRRPG. The day he finally manages to defeat the game's final boss, it curses him with its dying breath and kills him in real life! With a little help from a carefree goddess, Satoshi finds himself reincarnated into a mysterious new world as his in-game character, the incredibly powerful Great Sage known as Zelos Merlin. He accordingly decides to use his newfound powers to...continue living a quiet life on another farm! But first, he'll have to fight his way out of the vast, dangerous forest he woke up in—thanks a lot, goddess—and it won't be long before he's running into bandits, getting roped into teaching a young noble girl magic, and much more. Will the almighty Great Sage be able to conquer the toughest quest of all: getting some peace and quiet? (Source: J-Novel Club)

A middle aged man reincarnates in another world and becomes the strongest tutor in the world! Satoshi Osako (40), who had become addicted to the game and rose to become a top player, had an accident while logging in that put an end to his life. In a world full of swords, magic, and monsters, he was reborn with all previous statuses and somehow ends up tutoring a young girl… The diary of a wise man who lives in a different world, where his motto is “Peace and tranquility every day.” *Source: Manga UP! Global*