Yuragi-sou no Yuuna-san OVA

Episode 4

Bundled with the 24th volume of the manga. Hibari and Sagiri were on a mission for squadron. Their target was a dangerous ghost, a spellcaster. There, Kogarashi was doing his part-time job. When he nearly defeated it, the ghost threw a powerful spell on him . Now, the spell can only remove by seeing twelve panties or he'll die.