From Tokyopop:
Sasshi’s world is in disarray. His best gal pal, Arumi, is about to move away, and his Osaka neighborhood is being demolished in the name of urban renewal.
However, this little neighborhood has some surprises under its concrete -- it’s actually a portal to parallel universes. And when this section of the city is leveled, the portal is cracked wide open. Sasshi and Arumi soon find themselves being hurtled from one strange world to the next! Making matters even more surreal, is the fact that these worlds seem to spoof and mock popular movies, video games, manga and anime!