Ikai Tettai Parabellum

Summary

A popular high school student, Oma Higurashi, falls fast asleep on the train while heading home. When he wakes up, he finds himself at an unfamiliar station. Crashing into the station building labeled "Sasaragi Station" is a missing girl named Mayuru. As a sudden gunfight erupts, Oma realizes that he has wandered into a strange, otherworldly realm he has never known.