Katsuragi Mai

The protagonist's sister-in-law who acts harsh towards him. She has a bright, but assertive, personality.

Due to her reluctance to show her weak side to others, she is particularly stubborn towards the protagonist.

Towards her husband, she is usually polite and unable to assert herself, perhaps because she is in love with him. Because of this, even after their daughter was born, she is secretly unhappy with her husband, who is away on a business trip and rarely comes home, but she can't bring herself to say anything.