In a time when dreams seem out of reach, a teen fencer pursues big ambitions and meets a hardworking young man who seeks to rebuild his life.

A CODA (child of deaf adult) student born with a gift for music crash lands at an unfamiliar place after time traveling through a suspicious music shop. There, he forms the band Watermelon Sugar with other mysterious youths.

Yeon Shi-eun is a model student, who ranks at the top at his school. Physically, he appears like a weak boy, but, by using his smarts, tools, and psychology, he fights against violence that takes place inside and outside of his school.

When hijackers seize a Japanese flight and demand to fly to Pyongyang, a mysterious mastermind hatches a zany scheme to reroute the plane to Seoul.

Mantis, an ace assassin, returns to the contract killer industry after a hiatus, encountering his trainee friend Jae-yi and a retired legendary killer Dok-go, who now runs the organization.