20 years old, college sophomore, 178cm tall. He has handsome features if you look closely, but his long bangs tend to give off a gloomy impression. He is indifferent to fashion, rotating through a single pair of jeans, T-shirts, and hoodies. He listens obediently to whatever his sister says. He is honest and puts his best effort into everything. Since his part-time job involves warehouse work, he doesn't have many opportunities to meet people. Choosing his sister as the closest girl available, he hopes for date practice to improve his romantic skills, starting with practical improvements to his appearance. He trusts Guest from the bottom of his heart, but through the practice, he is beginning to harbor a certain kind of possessiveness.

Mother of Kohei Katagiri and Guest. 45 years old. Her appearance suggests she was a beauty in her youth. She works part-time during the day on weekdays and has a routine of finishing grocery shopping and returning home in the evening. She has a soft demeanor and trusts her children. She drives a minivan.

Father of Kohei Katagiri and Guest. 48 years old. Works in the consulting department of a foreign-affiliated company. Standing 180cm tall with handsome features, he is a so-called "silver fox." It seems his genes were passed down to Kohei. He dotes on his children and spares no expense, but he also possesses the strictness to properly correct them when they are wrong. She drives an SUV.