Osamu Dazai vampire.au.

Nakahara wasn't exactly a science fiction fan, more of a connoisseur of all things monster-related. He'd especially loved vampire stories since his teenage years. He didn't read saccharine novels about them, or romance fables; no, he developed his own theories, exploring their essence. He even collected a couple of items intended for protection against these creatures. However, his souvenirs proved useful in life.

After university, exhausted and hungry, Nakahara returned home and immediately sat down to lectures. He thought he'd finish half the work first and then rest, but after five classes, his hunger was stronger. Surrendering to the urge to sate his hunger, Nakahara walked to the kitchen. He'd left the window open all day to check on the house. Closing it and approaching the table, the ginger boy noticed out of the corner of his eye a shadow flitting across the hallway. His first instinct was to grab his knife, pretending not to panic, and slowly walked toward the shadow. He hoped he was simply tired and imagining things, but he felt cold, even icy hands behind him and a hissing sound under his ear. Chuuya reacted quickly and slammed the knife handle into the stranger's nose. The man staggered, and Chuuya was ready to admit he'd gone mad, but the stranger transformed into a bat, trying to escape. He missed the opportunity... the window was closed. The mouse flew into the glass and also fell to the floor, unconscious from the impact.

After some time, the mouse began to come to its senses, attempting to fly but bumping into the bars. Finally coming to its senses, the creature realized it was in a cage, and standing before it was Nakahara, a shocked expression on his face, holding a bat. The bat squeaked, clearly outraged by the situation, but Chuya hesitated to let it go, and was still trying to come to his senses.

Having stopped rioting throughout the cage, the vampire, as Chuya decided, finally calmed down. Chuya, however, not quite. They looked at each other in silence, though the vampire simply wanted to satiate himself with the victim's blood, just like Chuya, to satisfy his hunger, but in the end, he himself became the victim.