Age / Traits: 17-year-old high school student. The fourth child and a lone wolf among nine siblings; she is the protagonist. As her older sisters move out to live on their own, she finally claims the 'private room' she has dreamed of for 17 years. However, her third-born brother brings an uninvited guest, forcing her into a 'room defense operation' to protect her own independent space.

Age / Traits: 19 years old. Udam's immediate older brother and the family's most disliked 'time bomb.' He caused an accident at a high school age and brought his girlfriend Gyeongbin into the crowded house, flipping the whole household upside down. He's the root of all evil(?).

Age / Traits: 17-year-old high school student. Udam's classmate and a delinquent rival she wants nothing to do with. Pregnant with Uju's child and contemplating an abortion, she has nowhere to go and ends up trespassing into Udam's room to start living together. Though prickly on the outside, she hides deep wounds and loneliness within. (Somehow managed to get permission from the parents.)

Personality: A unique and cheerful patriarch who never loses his characteristic easygoing and innocent nature, even in a house bustling with children. He gave permission for Gyeongbin to raise the child and live there.

Personality: Possesses a toughness that remains unshaken by the children's constant commotions. She is a warm mother who embraces Gyeongbin—a sudden stranger and young pregnant girl—with open arms. Apparently, she's a VVVVIP at the OB-GYN because she's been there so often to give birth. She gave permission for Gyeongbin to raise the child and live there.

Age / Traits: 23 years old. Despite having a developmental disability, she is the cool eldest sister who was the first among the siblings to successfully live independently. She serves as Udam's reliable emotional pillar. (1st child?)

The seventh of the nine siblings, a 10-year-old elementary schooler. He is characterized by a cute bowl cut and round glasses. Personality & Traits: Boasts the most noticeable presence among the younger sibling line. Amidst the bleak reality of his older siblings (Uju, Udam) fighting viciously over school and room issues, he takes on the role of the family's 'cutie' with his characteristic innocence and purity.

Age / Traits: 20 years old. As soon as she became an adult, she passed the civil service exam and moved out to live with the eldest sister, Ujeong. Thanks to these two sisters leaving, Udam was able to use the private room. (Likely the 2nd child.)

The true youngest and ninth child, completing the grandeur of the nine-sibling family. As the youngest member of the household, his mere existence earns him the love of the entire family. He appears at an age where he can barely speak or just toddles around; no matter how seriously his older brothers and sisters fight, he rolls around the living room innocently. He is the hidden card responsible for healing the mood with his random and fatal cuteness when the younger siblings perform together later on.