July That I Randomly Discovered

Dan-oh is an ordinary high school student experiencing some not-so-normal things. Days seem to pass in the blink of an eye, her memory's gone fuzzy, and she might be hallucinating. What’s going on? Turns out she’s a character in a popular romance comic! But no, she’s not the main character—she’s an extra with a terminal heart condition, engaged to a childhood friend who doesn’t love her and will eventually dump her. Frustrated by her limited time, Dan-oh sets out to find her true first love.

(Source: Tapas)

Note: Chapter count includes two prologues, one per season, and an epilogue.