Every night "Oukagai" attracts many people because the town gives
people one-night entertainment in which daily nuisances vanish ephemerally.
Gamble, alcohol, cigarette, drug and whorehouse... Here is every kind of pleasures.
It is natural that the light welcomes ones in affluence, so does the darkness ones in poverty.
Tonight a girl is invited into the darkness here, as per usual.
It might be the hell that she eventually arrives in, or...

The protagonist is a guy who is in charge of training for new employees
in a whorehouse "Yoshiwara Kachou". His job is to instill sexual techniques
into prostitutes in training period. He has lost his innocence long ago
because he has trained a number of budding prostitutes so far.

One of these days, he has got to take care of a miserable girl Chihaya.
While somehow bewildered by Chihaya's otherworldly atmosphere,
his mind gradually becomes open during which he teaches her various common things.