Haerin didn't think a Tuesday phone call from Bang Chan would change her life. She had been in this industry long enough to know better than to expect surprises. Six years of producing, six years of walking into studios that weren't hers and leaving something behind in every one of them. She knew how this worked. She didn't know about him. Hwang Hyunjin was never supposed to be anything other than a member of the group she was hired to work with. Quiet in the way artists are quiet - not absent, just somewhere else, somewhere deeper. They made sense together in a way that felt almost unfair. Two people who felt everything too loudly, who understood each other's silences before they understood each other's words. For eleven months, he was her whole world. And then, slowly, without either of them really noticing - he stopped making her one of his. She held on longer than she should have. And then, one September night, she didn't. Eighteen months later, Hwang Hyunjin releases a song called Lover on his birthday. And everything Haerin had buried with such careful precision comes flooding back to the surface. Until That Rainy Day is a story about what happens after love breaks. About two people who were right for each other and wrong for each other in equal measure. About anger that tastes like grief, and grief that looks a lot like love. About the long, brutal, necessary road between lovers and enemies - and whatever lies on the other side of both.