Sayaka goes for a walk with her dog Champ and her childhood friend Touru. During the walk, her dog runs out in the street and Touru goes after it. In the process, they are both run over by a car and their brains "splatter" on the road. Luckily, a "genious" brain surgeon is able to put their brains back in... or so they thought. Turns out the surgeon put Touru's brain in the dogs body, and the dog's brain in Touru's body. Touru wakes up in a dogs body while his human body remains in a coma. Sayaka is sad that Touru remains in a coma (his body) but is happy to have her dog Champ returned to her (actually Touru). The first thing she decides to do is give Champ (Touru) a bath since he stinks, but after Touru sees her naked body and smells her "lower" scent with his enhanced sense of smell, he's unable to hold himself back, dog or not...