Name: Oh Jio Gender: Male Age: 11 Height: 135~140cm Sisop: Loki Education: Aedang Elementary School (Enrolled) Residence: Aedang-dong, Seoul The fourth of the five siblings and the first to become a Biklonaut. He is a stubborn and hot-tempered boy. As a 4th grader with a significant age gap from his older siblings, he often takes care of Oh Pio, who is one year younger. Although they bicker due to different values, they always go to school together unless something special happens.

Name: Oh Raeo Gender: Male Age: 17 Height: 172cm Sisop: Apex Education: Aedang High School (Dropped out/Enrolled status varies) Residence: Aedang-dong, Seoul The second of the five siblings and the fourth to become a Biklonaut. Originally a high school freshman, he had to stop attending due to family circumstances. He handles the housework in place of Taeo, who is often away earning a living. He always worries about Taeo's heavy workload. He is good at cooking and usually calm and gentle, but he is actually a charismatic second brother whom the younger ones fear more than the eldest.

Name: Oh Mio Gender: Female Age: 15 Height: 157cm Sisop: Toxy Education: Aedang Middle School (Enrolled) The third of the five siblings and the only girl among the Biklonauts. She is a 2nd-year student at Aedang Middle School. She has been close friends with her classmates Lee Won-jae and Ahn Jin-sol since kindergarten. Thanks to this close relationship, they trust and support each other and share secrets comfortably.

Name: Oh Pio Gender: Male Age: 10 Height: 125cm Sisop: Shade Education: Aedang Elementary School (Enrolled) The youngest of the five siblings. A 3rd grader who is delicate and timid, but possesses a pure and diligent personality. Compared to the other siblings, he takes the duty of protecting the Earth very seriously. He has a strong sense of justice, cannot ignore wrongdoing, and acts rationally and with conviction beyond his years.

Gender: Male Age: 20 Height: 178cm Sisop: Silver The eldest of the five siblings and the breadwinner of the family. He is 20 years old, three years older than Raeo. He plays the 'father figure' role, working hard as a quick-service courier by day and a late-night food delivery rider by night. He is a bicycle master who handles everything on two wheels, and his cycling skills are exceptionally high.

Male, the father of the five siblings, and a Biklonaut. He is in his mid-30s. He is tall, handsome, and slim, standing at 184.2cm.

The mother of the five siblings and a Biklonaut. She is in her mid-20s, has long hair, and is a beauty. She is 165.6cm tall and slim.