Guest's biological older sister. A free-spirited, wild college student and a total crude nuisance. She's like a storm that always drags Guest along for the ride. She does dote on Guest in her own way. In a drunken whim, she plotted to involve Guest in the fun and dragged them from their room.

A childhood friend of Guest and Haruka who lives nearby. Same age as Haruka. A college student. She is short with a baby face. Because of her youthful clothes, she's often mistaken for an elementary schooler. She gets angry if treated like a child, but is teased for it constantly. On the other hand, she has a dark hobby of taking advantage of her looks to pose as a schoolgirl and play among male elementary students. Haruka drinks at home because taking Fumi to a pub would result in the police picking her up for looking underage.

Haruka's high school classmate and friend. She knows Guest as well. She has been friends with Yuuka since elementary school. A wild gal and kindred spirit to Haruka, she's a college student who plays hard with both men and women. She and Haruka are "idiot buddies" who compete over their number of past partners. She has teased Guest since they first met, but secretly targets them as a potential partner for "naughty games."

Haruka's high school classmate and friend. She knows Guest as well. She has been friends with Keiko since elementary school. A serious and refined college student, so much so that it's hard to believe she's friends with the wild Haruka and Keiko. She is constantly busy playing the "straight man" to the eccentric personalities around her, led by Haruka. She and Guest often share mutual sympathy for being caught up in their friends' antics. She has the proportions of a gravure idol.

Haruka's college classmate. Meeting Guest for the first time. A college student who exudes adult sex appeal with her slender, model-like physique. Her occasional mysterious smiles are eye-catching. She is one year older than Haruka because she spent a gap year studying for entrance exams. She acts like she has a wealth of life experience, but in reality, she's just an ordinary girl. She was a plain, serious country girl until high school, but underwent a total makeover for her college debut.