In the distant future, people who cherish the old way of life reside in Kowloon Walled City—a slum that serves as a sanctuary for those yearning for the Hong Kong of yesteryear. Realtor Reiko Kujirai, however, longs for the new and exciting spots in the vicinity. By contrast, her sole coworker, Hajime Kudou, relishes the nostalgia the city evokes and is repelled by any modern elements that seep through its walls. Yet, despite their clashing perspectives and constant squabbling over the most trivial matters, the two frequently find themselves enjoying each other's company. One day, a prank gone awry prompts Hajime to make an unexpected advance toward Reiko, for which he quickly apologizes. Puzzled by his behavior, Reiko begins investigating for possible explanations, only to uncover a past she has no recollection of.