Following her grandfather's recent death, Hamaji Ooyama lives out her days on an isolated mountain hunting for food and caring for herself. One day, Hamaji's brother, an aspiring samurai living in Edo, sends her an invitational letter to end her solitary life and join him in the city. When she arrives, however, she is met with a grisly sight—the heads of six dogs displayed for all to see. These heads belong to the Fuse, a group of eight human-dog hybrids that have been terrorizing the people of Edo. Hamaji assists a strange man escape a group of assailants and makes it to her brother's house, where he asks that she help him collect the heads of the remaining two Fuse, as well as the Shogunate-sponsored bounty. But it is easier said than done—as the Fuse can blend into human society almost seamlessly—and the kind man Hamaji had just helped showed the Fuse's telltale signs.

The world of psychology is far from strange to the unusual Dr. Ichirou Irabu, a resident psychiatrist of Irabu General Hospital. He and his charming nurse Mayumi run through several patients, each suffering from a mental illness that harms their everyday life. Patients should be wary of the seductive Mayumi, with her spellbinding looks and devilishly short pink nurse uniform. On the other hand, the doctor seems to have three separate personalities: a child with an oversized lab coat; an intelligent, youthful man with feminine traits; and a selfish, outgoing green bear. While curing his patients in questionable ways, Dr. Irabu often tries to gain something from them outside of his profession—and in doing so, occasionally forgets his role as a doctor. As each patient struggles to face the nature of their distress, an obvious yet invisible thread ties their paths together.