Death March kara Hajimaru Isekai Kyousoukyoku

Suzuki Ichirou, a 29-year-old programmer, finds himself transported into the game he was creating.

In "the game," he is named Satou and is 15 years old. Although he initially thought he was dreaming, he realizes that his game is a bit too real.

Due to his immense power, he can decimate an army of lizardmen in an instant.

He decides to hide his power to meet and live peacefully with the different inhabitants of this world; however, events pre-planned in his game (like the return of the demon lord) will get in his way.