An unnamed Japanese vending machine otaku is crushed to death by a falling vending machine. He then finds himself reincarnated in a fantasy world dungeon as a sentient vending machine. He can see and hear but is immobile, with his speech being limited to stock Japanese vending machine phrases, such as "Hello there" or "Too bad". As a vending machine, he discovers he can dispense any item he has bought in his previous life, and can convert such sales to points, thus sustaining his existence. He is also able to use excess coins to add additional features to his vending machine body, and is able to choose which items he stocks or the prices of the items. Furthermore, he is able to use some magical abilities, including shapeshifting, invisibility, telekinesis, and a defensive vector force field.
Stuck in the middle of the wilderness, he encounters Lammis, a young female hunter. Lammis has a skill known as the Blessing of Might, which makes her ridiculously strong, but is still a novice at managing her own strength. The two quickly become friends after he dispenses some food items to the hungry Lammis. Calling him "Boxxo", she starts carrying him around on her back, which allows Boxxo to move, with his weight allowing her to more easily control her strength. The series chronicle their adventures as they start exploring the world's dungeon, and the characters they meet on the way.