Chi-Sui Maru loves sucking human blood; an all-around normal mosquito. Conversely, Nobuo hates his blood to be sucked; an all-around normal office worker. Chi-Sui Maru is quite partial to the way Nobuo tastes, and in a quest for delicious blood, Chi-Sui Maru passes the days chasing down his main course. But, not being one to lose to a mere insect, Nobuo tries to put up a resistance. Source: ANN