Code-named Sev, Yu Ji-an is an S-rank agent belonging to Rest, a top-secret government assassin organization. Upon completing his 300th contract—a first in the organization’s history—he finally earns his hard-won retirement. Eager to leave his blood-stained past behind, Ji-an sets out to fulfill a modest healing bucket list he spent two decades planning, starting with a simple goal: earn honest money without killing anyone. He takes on a humble job at a convenience store, determined to accomplish his duty with absolute precision, but his quest for a peaceful life is constantly disrupted by unpredictable incidents and a suspicious woman who keeps crossing his path. Will the legendary killer manage to keep his hands clean and capture ordinary happiness?