Shinkansen Henkei Robo

"Unknown" is a mysterious enemy that suddenly appeared a long time ago. As a countermeasure, the "Evolutionary Railway Development Agency" (ERDA) has developed the "Shinkalion" robot that transform into bullet trains, to prepare for the threat. "I want to be a cool person who can protect something..." Taisei Oonari, a second-year junior high school student, transfers to Shinkai Gakuen Middle School in search of clues about his older sister who disappeared two years ago. Just then, the Unknown appears for the first time in 10 years.