Legend Of The Great Infidelity summary:

Utamaro Kogawa is a travelling salesman, always accompanied by his younger sister Hotaru, his only beacon of light and hope. Going from place to place, he fulfills the needs of his clients for a price. What sorts of 'needs' does this salesman fulfill? In a world ruled by the depravity of men, one can only assume nothing but the worst. With every request fulfilled, a glimpse is given into the dysfunctions between men and women.