Annas, a straightforward woman in her late twenties, lives alone in an apartment. One day, her younger male coworker, Hinata, moves into the unit next door. Hinata is a classic salt-type young man: cool, aloof, and hard to read, with a lean but unexpectedly muscular build. Soon after moving in, Hinata's bathroom breaks down, and Annas agrees to let him use hers for a week. What begins as a neighborly gesture quickly escalates when, swept up by the moment, the two cross a line and begin a physical relationship, much to Annas's internal conflict since she believes she should keep a proper distance from a valued junior colleague.

As they continue their arrangement, Hinata reveals a passionate and possessive side beneath his detached surface, and the pair gradually transition into an actual romantic relationship. Annas finds herself genuinely happy, doted on daily by the seemingly cool younger man. However, their newfound bliss is tested when a former boyfriend, Kiryu, returns to Japan after five years and asks Annas to get back together with him. This reappearance forces Annas to navigate her lingering past while solidifying her feelings for Hinata, deepening the central love story between the salty-faced junior and the strong-willed senior as they face external challenges together.