Sei Brunehilde Gakuen Shoujo Kishidan to Junpaku no Panty The Animation

Kabuto comes from an old clan with many customs, one of them being arranged marriage. Thus, one day, while attending boarding school, a woman named Miyako Ruriko appears before Kabuto and introduces herself as his fiancée. While Kabuto is not too eager to follow the traditions of his clan, Miyako is infatuated with her fiancé and wants to prove herself as an adequate wife. Therefore, the lewd Kabuto decides to put his fiancée to a test…