The seventh son of a temple priest, Nanasawa, hates himself for being able to read people's lifespan counters and lives an inconspicuous life. He meets a black-haired woman and is led to live in an apartment complex where he can't read anyone's lifespan... Nanasawa is happy, but that's only natural, as the complex is home to a population of youkai called Karasuyama Danchi. Hachi, a black-haired crow woman, sees through Nanasawa's strong-willed spirit and tries to have him give birth to a half-youkai baby so that the youkai can survive the turbulent times. With Hachi's help, female youkai arrive one after another hoping to receive the mercy of Nanasawa, but... what will happen to the hybrid youkai child-making project?!