あらすじ
“Don’t you think we’re missing that heart-fluttering feeling?” From elementary school all the way to high school, Nam Do-yeon and Jeong A-rin have gone from childhood friends to lovers. For a couple who strives for a perfectly rational relationship, a plan to reclaim that one missing piece of excitement. Operation: Heartbeat begins!
あらすじはAniListより（英語）。