Read Dungeon Seeker Manga:
Junpei Takeda, a high school student, is childhood friends with Noriko Tatsumiya and the bully Kido Shouta. One day, during the usual course of bullying Junpei, they were suddenly summoned to a different world by the whim of "God". Summoned Heroes with cheats, or so he thought. But it turns out Junpei stats were even worse than an average farmer. Tricked into a deathly labyrinth by the only one he trust, more.. he walks the journey for revenge.