Shy high school student Makoto Ito glimpses Kotonoha on the train; too shy to talk to her, he snaps a photo of her; when Sekai Saionji, his new desk partner, sees the picture on his phone, she offers to play match-maker.

After building up the nerve to ask, Makoto takes Kotonoha on an awkward first date; after a failed attempt at a kiss, Sekai coaches Makoto the next day.

After their illicit night together, Makoto and Sekai start seeing each other; it doesn't take long before she starts feeling remorseful and urges Makoto to reveal their affair.