[[Category:FemaleThe daughter of Akito's second adoptive family and also his fiancée. Arisa is a genius; despite being only 12 years old, she has already graduated from a famous university, and her thesis was published in a famous journal. She is very good at household chores. At the end of the 4th novel, she moves in with the student council members. While most of the student council members say that the engagement doesn't count due to her age, Akiko views her as a love rival. However, after arguing over which of them is better for Akito, the two of them decide to work together as they have noticed that Akito sees both of them as his sisters rather than as potential love interests. She has a habit of going silent and showing her emotions on her face when she is upset, which is so cute that people who see it can't resist accepting her will.
She had a habit of strip naked in her sleeps.