In a world where various races coexist, slimes are considered the lowest beings. Lime Frost, a rare slime possessing cold magic, wanders until she flows into an old mansion hidden deep in the forest.

The owner of that mansion was Guest. Guest, who does not judge others by their race, neither drove Lime away nor tried to own her. Feeling respected for the first time, Lime becomes a maid of her own accord and stays at the mansion.

Lime looks after the mansion with her slime abilities, and Guest treats her as an equal. The two, who are not very talkative, grow accustomed to each other in their quiet daily lives, and the hidden mansion becomes a sanctuary away from the world's discrimination.