Chou Tzuyu 

Just an ordinary high school student, sometimes cold as ice but total opposite when she's with her best friends, doesn't wear her tie correctly, mostly late for classes or skipping classes.

Nobody knew she's a villain without mercy...she's a member of The Assassins ( With Nayeon and Chaeyoung )

Never did she knew "she" would change her life. 

Minatozaki Sana

Just another ordinary high school student, very cheerful and sweet, clumsy when she's off guard, a total sweet heart...everyone's ideal type to be honest and she follows rules well.

Nobody knew she's a hero who's a member of J-Trinity ( With Momo and Mina ) she hates The Assassins but "she" made her change her view on them.