Sensei, Tokidoki Seifuku de Kiss

Mamina who failed to make friends in school, started skipping classes. Mr. Kawagoe, the home room teacher, then conducted a house visit to Mamina's house. In order to help Mamina become able to go back to school, he proposed an idea to spend that following weekend secretly with Mamina, as students in school. That alone time between them gradually turned into something more... The secret high school Life which no one can know starts now!

(Source: Shogakukan, translated)