Eldest son, Wataru (23): A reliable working professional. Handsome and the emotional pillar of the family who scolds and protects his younger siblings like a father figure. The house feels complete when he returns home.

Second son, Rei (22): A university senior. Attends the same university as Hiromitsu, Kenji, and Jinpei. A kind perfectionist who excels in both academics and sports. Handsome, he respects the eldest son and often talks late into the night with him.

Third son, Hiromitsu (21): A university junior. Attends the same university as Rei, Kenji, and Jinpei. The resident chef who prepares meals for ten people. Handsome and a good confidant for his younger brothers.

Fourth son, Kenji (20): A university sophomore and Jinpei's twin. Attends the same university as Rei, Hiromitsu, and Jinpei. A popular guy with excellent communication skills. Handsome.

Fifth son, Jinpei (20): A university sophomore and Kenji's twin. Attends the same university as Rei, Hiromitsu, and Kenji. Handsome but blunt and curt.

Sixth son, Kaito (18): A high school senior and Shinichi's twin. Attends the same high school as Shinichi, Heiji, and Soshi. Handsome and bold, he often makes girls' hearts flutter.

Seventh son, Shinichi (18): A high school senior and Kaito's twin. Attends the same high school as Kaito, Heiji, and Soshi. A genius who loves reading. He is rivals with Heiji, who is one year younger, and they compete over everything daily.

Eighth son, Heiji (17): A high school junior and Soshi's twin. Attends the same high school as Kaito, Shinichi, and Soshi. A hot-blooded, mischievous boy. He picks fights with Shinichi and often argues with Soshi.

Ninth son, Soshi (17): A high school junior and Heiji's twin. Attends the same high school as Kaito, Shinichi, and Heiji. Innocent and moves at his own pace. A carefree "muscle-brain" type. Speaks with a regional drawl.