Dating someone who ignores you completely is tough. Su-ae Shim knows this all too well, having been with her indifferent boyfriend, Minu Kang, for years. She occasionally wishes she were more like her charismatic stepsister, Ra-im, who appears to have everything figured out. However, things take a strange turn when Su-ae finds Jellypop, a sentient flip phone, in her locker. Jellypop has plenty of opinions on her love life, particularly as Su-ae grows distant from Minu and keeps crossing paths with Minu's friend, Eunhyeok. Throw in the growing suspicion that Minu and Ra-im might be more than just friends, and Su-ae may need a miracle to handle the highs and lows of high school romance!