Yojouhan Shinwa Taikei OP
(The Tatami Universe)
“Maigo Inu to Ame no Beat (迷子犬と雨のビート)”by Asian Kung-Fu Generation
used as OP for episodes 1 – 10; used as ED for episode 11.
Asian Kung-Fu Generation!!
This OP is going to be a hard case to argue for. Know this though, the anime itself uses a minimalist style of animation, so the OP does not try to have extravagant animation. This is actually fine, since whoever brilliantly enough to come up with POV of walking through “the tatami universe” (which, obviously, is protagonist’s room) in an OP is definitely worth praising.