In the heart of Akihabara, siblings Tamotsu and Niwaka Denkigai face a sudden threat when vampiric cosplaying monsters, the 'Bugged Ones,' swarm the district, spreading chaos. Amidst the turmoil, Tamotsu encounters one of these creatures, only to be saved by the enigmatic Matome Mayonaka armed with a baseball bat. United in their battle against the Bugged Ones, Tamotsu sustains a fatal injury shielding Matome, leading her to transform him into a powerful Bugged One like herself. Forming a quirky trio with the lively otaku cosplayer Arisa Ahokainen, they become 'The Electric Mayonnaise,' combating the monsters by stripping them down and exposing them to sunlight.