""It was 23:59. December 31, 1999. Out of the gap between the two centuries, a "Storm" poured upwards to the sky. The next second, all the parties, neon signs, and late night buses faded away. The world returned to a strange old era.

This young girl, the "Timekeeper," the only one immune to the Storm, has witnessed the beginnings and ends of countless eras. During her time travel, she makes friends with arcanists from different times and countries and then guides them ... to escape the "Storm.""