Green Tea Bitch (n.): A woman who pretends to be pure and innocent but is in fact manipulative and calculating.

When school ends, a good honor student is threatened by the class's green tea bitch.
"I never thought a wide-eyed goody-two-shoes like you would get up to something like that."
"If you don't want me to expose your shameful secret..."

A cute romance that stems from a misunderstanding begins in That Time I Was Blackmailed By the Class's Green Tea Bitch!

Note: School girl and School life are applicable to Season 1, while College and Couple life are applicable to Season 2.
Despite being in the title, Blackmail is only applicable early on in the series.