Kouki Bones (born July 4, 2027 in Osaka, Japan) is one of the adoptive sons of Louie and Joanne Bones and the vigintuplet brother of Takumi, Ayaka, Kenji, Mao, Ai, Yuki, Yoshi, Kenta, Yuta, Sakura, Sota, Ku, Megumi, Miyu, Daito, Tomoyo, Ren, Rina and Momoka.
Kouki is tall and skinny with snowy-white skin, jet-black hair and huge dark eyes. He wears a green Tom and Jerry T-shirt, black jeans and yellow sneakers.
Kouki is smart and well-behaved.
- Father: Louie Bones
- Mother: Joanne Bones
- Brothers: Takumi Bones, Kenji Bones, Yoshi Bones, Kenta Bones, Yuta Bones, Sota Bones, Ku Bones, Daito Bones, Ren Bones
- Sisters: Ayaka Bones, Mao Bones, Ai Bones, Yuki Bones, Sakura Bones, Megumi Bones, Miyu Bones, Tomoyo Bones, Rina Bones, Momoka Bones
- His full name is Kouki Jonny Bones
- He likes playing with his toy trucks and sketching
- He and his vigintuplet siblings are fans of Pokémon
- His favorite food is pancakes
Kouki marries Brooklyn Ross and has three children, Susan, Dolly and Peter. He works as an artist.