Responses
Is it perhaps Fake na Junjou? It is remedy class though, not cram school, and the student is 5 not 6
But, maybe you can check it first :)
http://www.mangago.me/read-manga/fake_na_junjou/
im looking for a yaoi about a teacher x student. if i remember correctly, its a small cram school only like 6 kids. one is in love with the teacher and he dosnt hide it but the teacher dosnt take him seriously at all. thats all i remember sadly :(((