Heaven and hell. A realm of angels, a realm of demons.
Two opposite worlds connected by a "gate", a neutral vast stretch of space.
The two worlds rarely interact, due to the negative effects of
each realm's "silk" which cripples anyone from the opposite.
Somehow, demons sneaked into heaven and stolen one of their treasures, the forbidden mirror.
Queen Anastasia calls on angel Sakura to go to hell and bring it back.
Sakura is immune to the effects of silk... but not to its many other threats!