Segawa Kiichi, a former delinquent, happens to encounter a lonely 10-year-old girl who looks like she is going to be killed by the Yakuza. He saves her by reflex and later realizes that she lost her memory. She doesn't know why the Yakuza are after her and Kiichi is attacked time and again because of that. With his own life in sudden danger, he calls on six friends from his high school days as a delinquent. These enthusiastic, single-minded men band together to protect her to the end.

Rookie police officer Chinami (Emi Takei) is assigned to work on the investigation team. On her first day, she is designated for assignment. Chinami is teamed up with a handsome detective. They work together to solve difficult cases, while Chinami often gets scolded by the veteran detectives.

Suzaku Kanade is the scion of the Suzaku Group who is a bilingual "straight A" student with good looks and great athletic abilities. He is deemed a "celebrity prince" with graceful manners. One day, through his father's introduction, Kanade meets "bad boy prince" Kyogoku Takato who is a charismatic figure among the bad boys in the downtown area. Kanade and Takato who live in completely different worlds and have totally opposite personality start to compete for an "important thing". However, Takato's little brother Kyogoku Ryu, student-union president prince Ayanokoji Aoi, dance prince Red - Tendo Koki, teacher prince Yuki Riichi, and beautician prince Sagasawa Haru also join the competition...