Mysterious Campus Tour

After graduating from high school, do you have to go back to your alma mater in junior high school to get your stamp of approval? ! It happened that the parents' meeting secretly took the school bus to save money. The first bus had already left, so I had to shamelessly take the second bus with the children. Is it so embarrassing to meet the former teacher... I didn't understand the meaningful look in the teacher's eyes, so I embarked on a mysterious journey...