Isekai Shoukan Wa Nidome Desu

From Coolmic: There was once a hero who was summoned to another world, and he saved that world. On top of that, he had to start over as a baby. This is the story of a crazy journey in another world where a former hero who was reincarnated into a slightly gloomy high school student is “resummoned” back to that same world. There’s a lot of room to work with when it’s the second time, huh