I apologize if I am doing this wrong, because I am not very good with technology. There is a manga, I think it is a shounen ai, but it may be yaoi. It involves an older teacher meeting a newer teacher who used to be his student. One thing I remember is that he was his student when he was a tiny kid, and that he was being abused by his family, which was found out by the teacher when the kid came in with a mask on claiming he had a cold. There is also one which I believe is a different manga, but it is similar in that it is a new teacher that used to be the student of the older teacher. But in this case, the teacher used to do cart wheels or flips or something for the students, but now he is older. The new teacher remembers this, and the old teacher eventually does it again. Please let me know if you know the names of these two mangas, and I apologize if I was to vague.

Second one seems like
Aozora no Sunda Iro wa