Eri Yukizaki, is a girl locked in battle with a chain-saw wielding incantation of true evil. But like the demons that boil inside her heart, the 'Chainsaw Man' doesn't seem to die no matter how much she stabs him. As she fights, a young man, Yamamoto watches, love-struck, wishing he could be more than just her useless bicycle courier.
An action-packed romance, digging into the human psyche, exploring the demons that buries us in sadness and misery.

From Tokyopop:
Sato Tatsuhiro is a drug-addled "hikikomori" (a Japanese shut-in) who thinks a sinister organization, NHK (Nihon Hikikomori Kyoukai), is the cause of all his problems! He falls in love with a girl, Misaki, who he thinks is trying to assassinate him, but doesn't know how to talk to her or if he can trust her. The more he stays in his house watching anime porn, reading manga, and doing drugs, the harder it is for him to leave. Only Misaki can keep him from rotting away in his own apartment!