High-schooler Hajime Nagumo is bullied by his classmate for his relationship with the class idol, Kaori.
When he and the rest of his class are transported to a fantasy world, all of his classmates get powerful magical abilities, while Hajime only gains the basic alchemical magic to transmute solid materials, a common ability usually found in craftsmen and smiths.
During a dungeon raid, he is betrayed by one of his classmates and dropped to the bottom of the dungeon. He survives the fall and creates weapons to escape the dungeon and become stronger.
On his journey, he meets with the imprisoned vampire Yue, and later is joined by the bunny-eared Shea, the perverted dragon Tio, and others.