Ateya no Tsubaki

Housen is a painter of erotic art in the Edo period, who stumbles into a murder mystery involving women who have hooked up with one of his patrons. With the help of Tsubaki, a girl he runs into on the street who seems to know more about him than he does and is an artist herself, they start unraveling mysteries involving sex, murder, and occasionally the occult...
(Source: BakaUpdates).