Sword Art Online: Project Alicization, Vol. 1 (manga‪)‬

“This might be a game, but it’s not something you play.”
— Akihiko Kayaba, Sword Art Online programmer
With no memory of how he got there, Kirito wakes up in a mysterious virtual world, and it’s up to him to find a way back home. But with no way to log out and no idea what kind of land he’s found himself in, he’s going to need allies! As a new tale unfolds, Kirito’s journey through the Underworld begins!