Akiba's Trip The Animation - S01

Otaku siblings Tamotsu and Niwaka Denkigai are shopping in Akihabara when the place is overrun by vampiric cosplaying monsters. These creatures, known as "Bugged Ones," can possess anyone they bite, and soon they start causing chaos across the city. When Tamotsu finds himself at the mercy of one of these creatures, he is saved by the mysterious Matome Mayonaka, who wields a baseball bat. Together they fight through several more encounters with the Bugged Ones, but before long Tamotsu is fatally wounded protecting Matome. With no other choice, she revives him as a high level Bugged One, just like her. Tamotsu and Matome, along with the excitable otaku cosplayer Arisa Ahokainen, form the group "The Electric Mayonnaise," and they begin dispatching the Bugged Ones in the only way they know how: by ripping off their clothes and exposing them to sunlight.