Seiso Kanojo, Ochiru.

Even though it's against the school rules for students to date, Tsukimi and Takagi have been going steady in secret for a whole 6 months. On a date at the amusement park, they finally share their first kiss, only for it to be caught on camera by an interloper. When the would-be paparazzo threatens to show the faculty, Tsukimi, being the good girl she is, goes along with his demands in order to preserve her and her boyfriend's academic standing.

(Source: Irodori Comics)