How I see, this can go one of three ways, depending on your favorites. Either Marinette, Alya, or Adrien.
Marinette because she is kickbutt as Ladybug, Alya because or her fierceness, Adrien... His dad is the fashion icon. So I'm writing for Marinette because that is what I thought first.
Marinette enters College Fracios-Duppont searching for the murderer of her father. Standing in her way is Bridgette, they student council President, and her elite four. Armed with a scissor sword and her life-fiber infused uniform affectionately named Plagg, Marinette is not going to let anyone or uniform stand in her way.
Whose who:
Ryuuko - Marinette/Alya/Adrien
Satsuki - Bridgette/ Didn't think this one through/ Felix
Mako - Alya/Marinette/Marinette
Senketsu - Plagg
Aikurou - either Jagged stone or Theo
Nonon - Alix
Ira - Ivan
Houka - Max
Uzu - Kim
Ragyou - Sabine/Mrs. Cesaire/Gabriel
Nui (aka Loli Bitch) - Chloe
Isshin - Tom/Otis Cesaire/Mrs. Agreste
Check my anime list for pictures on whose who. You might be able to figure it our based on personality pairings.