How Yabecchi got into this situation is best left to the imagination.
The Web Radio. One of the most universal forms of information and stories that most fans don't really listen to. Nonetheless, they remain a source for music in the anime world. Mitsudomoe's radio single has the OP (sung by the triplets) and the ED (sung by Yabecchi and Futaba). To watchers of the show, you may have heard the ED on the TV in the final broadcast episode and were wondering where to get it. The answer - here.