Matataki no Ao wo Tadotte

Yamato Tsukimachi, who has fulfilled his dream since high school and works as a teacher, finds a familiar name in the list of transfer students one day. "Isshin Komiya"—that was the name of a former best friend who fell ill and was unconscious when he was in his third year of high school. He says that Isshin, who regained consciousness two years ago, has been transferred to rehabilitate and restart his high school life. Although it's a different kind of teacher and student than before, the two have met again like a dream, and decided to fulfill the "list of things to do before graduation" that they couldn't do in the past.

(Source: Ichijinsha, translated)