After leaving college, aspiring writer Lee Jong-su is working a series of dead end jobs in Seoul to make ends meet. While delivering stuff he bumps into Shin Hae-mi a chilhood neighbour from the poor area near the DMZ where they both grew up. He doesn't recognise her at first but the two meet later and reminisce.
She persuades him to look after her cat while she is away on a trip and the two end up hooking up when they meet to sort this out. With Hae-mi gone away Jong-su waits eagerly for her return, diligently feeding the cat, which he never sees.
When Hae-mi flies back into the country she introduces Jong-su to urbane affluent trustafarian "Ben" who she met on vacation and it's very quickly apparent that he's been replaced romantically.
Regardless, Jong-su awkwardly continues to hang around with the pair, getting a taste of a life he can never have until one day he comes to suspect that Hae-mi is not safe with "Ben".