I'm the Hero's Substitute, but I Don't Need Companions Anymore

Daigo Kariya, an ordinary high school student living through dull days, is invited to an Isekai as a "Hero" by a Goddess who suddenly appeared. "If I go to another world, I can become someone " With such expectations in his heart, Daigo decided to go to the Isekai, only to be given the role of "Proxy Hero"……!? In an Isekai completely different from his expectations, Daigo's hellish days of fighting alone for survival begin――.