In the distant future, individuals who adore the old way of life live in Kowloon Walled City—a slum city that serves as a refuge for those who long for the Hong Kong of the past. Realtor Reiko Kujirai, however, craves for the new and exciting places in the area. In contrast, her only coworker, Hajime Kudou, enjoys the nostalgia the city invokes and is put off by anything modern that seeps past its walls. But despite their differing views and constant bickering on the most mundane of things, the two often find themselves enjoying each other's company.

One day, a prank gone wrong leads Hajime to make an unexpected advance toward Reiko, after which he swiftly apologizes for. Baffled by his actions, Reiko starts investigating for possible explanations, only to discover a past that she has no memory of.