*It's the upbeat song with a female voice singing "yeah yeah, na na na na na"...Or something. S: It's NOT "So What" by Pink or "New Look" by Namie Amuro. It's actually the other song. d:
Plays at: 11:43<- Plays the longest at this part, 12:47, 13:21, 14:09, & 23:06.
Hope this information helps. :D
& Sorry! It's just that this part is stuck in my head and it's so catchy! XD
Found it! It's "Sha na na" by MINMI. Thanks, asakurahao. ♥