Suterareta Yuusha no Eiyuutan - Story 3-1: 『Chance』

Michael, formerly a military veteran turned mercenary, was living quite a peaceful and slightly eventful life. That was until an accident happened that caused him great misfortune, rendering him unable to continue being a mercenary. After that point, his life spiraled into that of an alcoholic, eventually leading to his demise. Before he died, he saw something odd; it was a blue hologram with the words ’Do you wish to start anew?’ Michael readily accepted and was thrust into a fantasy world with a mysterious system companion that seemed to be hell bent on making him the best healer in the world. However, as he began unraveling mysteries, he found out his identity was not as simple as it seemed.

She fought in the Battle of Changping and witnessed the killing of hundreds of thousands. She once led the Qin Iron Calvary and battled against the Six Kingdoms. She has seen a third of the land and witnessed the breaking of mountains and rivers. The sound of a grand zither and the light of a great female emperor. A prosperous world that was forged on the battlefield. Yet, these two thousand years are forgotten from history.

- Description from Novelupdates

Suddenly a high school student Subaru Natsuki has been summoned to another world on the way back from the convenience store. With the biggest crisis of his life being summoned to another world and no sign of the one who summoned him things become worse when he is attacked.