Between Gray and Blue

Koutarou is a high school teacher who is ordinary in both looks and personality, and has a reputation as a "boring man." His father-in law, Koushi, somehow remains charming despite being over 50 years old. Koutarou's student, Sayotani, goes through one man after another with his youth and beauty. These three people who are ages apart connect with each other through Koutarou... (Source: Printemps Shuppan, translated)