Demon King Daimao

Demon King Daimao is a light novel series that received an anime adaptation which aired in 2010.

Set in a time where magic has become commonplace, the story follows Akuto Sai, an orphaned teenager who transfers to the Constant Academy of Magical Arts in order to achieve his dream of becoming a High Priest. However, his dreams are dashed when the aptitude test he took upon arrival prophesies that he is destined to become the Demon King. As word spreads of this revelation, Akuto's school life becomes complicated as the school populace becomes to fear and distrust him, but he is determined to ensure that his future fate is not set in stone.

OP
Akuto is seen with his shirt unbuttoned.

Episode 3
Akuto and Hiroshi take a bath together, and Akuto's undershirt is torn after he's ambushed by a bunch of thugs.

Episode 5
Akuto investigates an underground hot spring, and later his shirt flies up.

Episode 6
Akuto visits the beach.

Episode 9
Both Akuto's shirt and undershirt are completely torn off by his power.

Episode 10
Akuto is wounded by Yamato, but he is rescued by Fujiko.

Episode 11
Akuto returns at the last second after surviving 2V's attack.

Episode 12
Akuto battles and defeats Hiroshi, Yamato, and the Gods' defense system.

Special 4
The girls use Akuto's and each other's bodies to warm up.

Special 6
Akuto gets wet and his clothes partially taken off after most of the girls ate cookies laced with Fujiko's magic powder.