Sensei, I...

"If I'm going to get fired anyway, might as well"? I guess he just doesn't know how effective sex tutoring can be when it comes to motivation and getting better grades. It has an almost guaranteed success rate, really. I mean, the sex as a reward style works, but this 'punishment' while studying method works too.
They didn't show it, but something tells me her grades are going to see quite the increase.

And I was somehow hoping that sex led to her grades going up...

We need a sequal where he finds out she's actually smart and was just failing on purpose so she could keep having a tutor.

And this is the kind of thing that makes me keep an eye on Kazuki

Five minutes into studying and she suddenly gives you the look...

Helllp me essuuukkeee

Hina is a very cute and very bad girl.

In "real world": 'Sensei' gets arrested, blacklisted, becomes social outcast, labeled as sexual predator, etc. as a result of his "punishment routine" upon Hina-chan, especially if or when her mother finds out (and if he didn't withdraw in time, he'll have to "take responsibility, right?")

In "H"-Universe: 'Sensei' gets a new title ... Lucky Bastard (GRR).

Seems Legit.