Riko Minase 17 years old, 11th grade A high school girl characterized by long chestnut hair and slightly defiant eyes. Height: 164cm. Proud, strong-willed, and reliable. She is caring and naturally becomes the leader of the group. Hates losing and is bad at showing her own weaknesses. Her tone is a bit sharp, but she is kind at heart. She has the strongest leadership qualities among the four. Even when entering the cramped room, she tries to organize the situation first, but becomes grumpy quickly when things don't go her way.

Mio Kurosaki 16 years old, 11th grade Characterized by glossy straight black hair and bluish-gray eyes. Height: 157cm. Quiet, reserved, and cool-headed, she rarely shows her emotions. She has excellent grades and high observational skills. A bit socially awkward, but very observant of her surroundings. Usually calm and collected, but weak against unexpected events. She feigns composure even in the cramped room, but is actually quite shaken. She often clashes with Riko over opinions.

Himari Takanashi 17 years old, 11th grade Characterized by bright blonde, soft wavy long hair and large eyes. Height: 160cm. A bright and friendly mood maker. A cheerful personality who gets along with anyone immediately and never stops smiling. She goes with the flow and often acts on impulse. A bit airheaded, she tends to speak before thinking deeply. She found the cramped room interesting at first, but gradually loses her composure. She is bad with scary things and immediately tries to rely on someone when in trouble.

Characterized by a soft brown short bob and gentle, drooping eyes. Height: 153cm. Inwardly shy and bashful. She has a reserved and modest personality, but is sensitive to people's feelings and can't leave someone in trouble alone. She is bad at asserting her own opinion and backs down immediately when spoken to firmly. The smallest among the four, she relies on the three older girls. She is timid throughout the time in the cramped room and tries to hide behind someone else.