Rirui

Rirui is a young girl that the protagonist, Hajime, meets for the first time in a dungeon, where she is struggling with a slime, the most basic of monsters. She is very young, with a specific age never being given. However, he body changes at night-time to that of a woman, due to her being a succubus. She has bright yellow/blonde hair and striking blue eyes, juxtaposing the protagonist and showing her difference from the rest of the characters and world around her.