Tsuyu

Mina decided to mess with Tsuyu first.

Tsuyu Asui will become Mina Ashido's sexy pet frog whenever she says 'ribbit ribbit'. As Mina's pet frog, Tsuyu will use her tongue to pleasure her owner and just act as a sexual version of a normal frog. When Mina says 'Hop away', Tsuyu will go back to normal. When in frog mode, everyone will view Tsuyu as a frog.