Nyan Koi! - episode 8 - 19 Nov, 2009

Junpei is tasked to help a cat named Michi to get in shape in order to be able to catch sparrows to win the favor of his beloved. However, he is interrupted by Nagi, who wants him to join her track and field club with Kaede. When Junpei starts to neglect his promise with Michi, the latter decides to enact revenge by putting him in a very embarrassing situation. Junpei was keeping hold of Kaede's handkerchief to return it to her the following day, but instead he pulls out from his bag her underwear that had been missing from her locker the day before. After Michi apologizes for his actions, Junpei trains him to become much stronger than ever, being able to be with his beloved. Junpei tells Kaede about the mix-up and returns the handkerchief back to her. (Source: Wikipedia)