Completed Boy And Girl In Branch School; Bunkou no Hitotachi; DOORS (Yamamoto Naoki) ;分校的人们

Read Bunkou no Hito-tachi Manga:
Yoshida ♂ and Dobashi ♀ are the only students at a branch school in the countryside. They are later joined by a third student, Kobayashi ♀.
Vol 3 includes a 4 chapter extra story, DOORS.