Kashima Ryuuichi, A high school student. After the death of his parents, he and his younger brother are adopted by the chairwoman. He cares for his brother and works at the school's daycare outside of lesson hours. He is considered likeable by the daycare children and practically everyone he meets. 16 years old

​Hayato Katani, Ryuuichi's stoic classmate and fellow Babysitting Club member, who is also the older brother of Taka who addresses him as aniki. 16 years old

Nezu Chuukichi, Tomoya's best friend and classmate in the advanced class (1-A), where he is ranked 2nd (to Inomata). He is considered very practically smart, as a result of coming from a poor background and having five siblings. 16 years old

Usaida Yoshihito, The sleepy daycare worker and only official employee at the Morinomiya daycare. He is secretly an earnest and hard-working person. 23 years old

Kotarou Kashima, Ryuuichi’s quiet younger brother, who is deeply attached to him after being raised primarily by him while their parents traveled. Though soft-spoken, his expressive face shows his emotions, and he is beloved by everyone at the daycare. 2 years old.

Taka Kamitani, Kamitani's bratty little brother and one of the children at the daycare. The son of science teacher Shizuka Kamitani and chemistry teacher Taizo Hebihara. Despite his confident nature, he actually cries easily. He is Kotarou's self-proclaimed best friend. 2 years old

Kirin Kumatsuka, The oldest girl in the daycare, Kirin is the daughter of the drama teacher, Yayoi Kumatsuka, and a freelance photographer, Satoru Kumatsuka. She's very sweet and friendly, but has a stubborn side that can cause her to argue with Hayato. 3 years old

Takuma Mamizuka, The older, energetic Mamizuka twin. A son of PE teacher Umi Mamizuka and actor Kousuke Mamizuka. He is cared for at the Babysitting Club. 2 years old

Kazuma Mamizuka, The younger, teary Mamizuka. twin. A son of PE teacher Umi Mamizuka and actor Kousuke Mamizuka. He is cared for at the Babysitting Club. 2 years old

Sawatari Midori, The only baby in the daycare and normally under Usaida's responsibility. The daughter of Yukari Sawatori, who works in the high school office, and Yutaka Sawatori, an archeologist. 6-10 months old