Saikyou Saiaku no Mahou Shoujo ~Ecchi mo Mahou mo Bakuhatsu yo!~

He's a pitiful would-be villain. She's a massive arrogant heroine.

Nobody knows the battle that's about to be waged over this small town.
When Dr. Kawahara plots to claim it as his own, he's confronted by Azusa, a young girl.
As a "maho shojo" she can summons magic powers to vanquish her opponents.
Blam! That's how fast he's going to go down, she taunts.
Azusa is merciless -- something in her past made her this way. Some trauma.

With a trance-like face Azusa wields the metaphorical sex hammer of punishment that crushes Dr. Kawahara.
Magic is her stress outlet, and the crushing... well, that's just a perk. It's clear that while
she's technically defending the town, she's far from a beacon of purity and justice.

[from DLSite English]