Characters:

Kim Jieun:
Jellywool university's most hateful nerd but the nerd thing was only her camuflage,she actually the youngest member of “Seoul most scary gangster” just like her brother,Kim Sungkyu―infinite's leader― but she isnt part of her brother is gang.
Her gang―stage name is J―read as ji.

Lee Hongbin:
Another best fighter from another gang,but his group was infinite's bestfriend―named vixx― and had huge crush on Jieun but he scared for the dear life he would break the friendship if he confess to her.
Goes to Jellywool univ with Jieun Yejin Ravi Sungjong Hyuk.

Kim Yejin (Jieun's bestfriend):
Jieun's very bestfriend yet Jieun considering her(Yejin) as her long lost twin because they had same surname and their oppa were in the same group―gangster. Just same as Jieun; she is part of “Seoul most scary gangster” because her brother was Kim Myungsoo―known as L― is infinite's best fighter.
Her gang―stage name is YJ―read as wayji

Cha Hakyeon:
Vixx's leader―N also known as Yejin's biggest crush but no one knows except her twin―Jieun yet he is so clueless about something called love since he was known as the second fearless person after Sungkyu. He consider Sungkyu as his hyung.

Kim Sungkyu:
Infinite's leader,most fearless person but so nice to his loved ones. Kim Jieun's older brother,loves her and being so strict with whom his sister will befriend.

Kim Myungsoo:
Infinite's best fighter also Kim Yejin's older brother. Just same as sungkyu; he loves his sister so much, sometimes become so strict about who will be her friends.

Infinite:
The Seoul most scary gang also Sungkyu and Myungsoo is gang,considering members:
Sungkyu Dongwoo Woohyun Hoya Seongyeol Myungsoo Sungjong.

Vixx:
Another Seoul most scary gang,infinite's bestfriend and right hand. Considering member: Hakyeon―N Taekwoon―Leo Jaehwan―Ken Wonshik―Ravi Hongbin Sanghyuk―Hyuk.

Other chara:
Bang Minah,Queenka group Girls Day's leader.
Im Nana,Queenka group After School's leader.