Yasunobu Hattori (服部 安信 Hattori Yasunobu) is Yamato Akitsuki's best friend since childhood and the often met whenever Yamato came to stay with Ayano Fujikawa. However, Yasunobu would frequently get Yamato in trouble, since Hattori would take advantage of the fact that Ayano's dormitory also contained a women's bath. He is a ladies' man that, according to Yamato, prefers perverted stuff over eating. He dreams of dating all the girls in the world and the legalization of polygyny in Japan. Yasunobu is often giving relationship advice to Yamato, with rather amusing results, due to the latter's being clueless and tendency to screw up. Even though he sometimes gets Yamato in bad situations, he usually has Yamato’s best interests in mind.
- The character name is derived from one of Kouji Seo's real-life friends.
- Much to Yamato and Miki Hashiba's surprise, Yasunobu has been a straight "A" student during high school.
- He and Miki recently have made cameos in Chapter 67 of A Town Where You Live where they were meeting each other during Haruto's class trip to Tokyo.