Shū Hagiwara (萩原 柊, Hagiwara Shū)is a teacher and the ex-boyfriend of Hina Tachibana due to fact that Shū is married, therefore his relationship with Hina for the last two years is an illicit affair and he also seems to have a good friendship with Reiji Kiriya.
Although Shū does not make a color appearance in the manga, his hair appears to be dirty blond in the anime and wavy with layers in design, blue eyes and glasses. He seems to have a very gentlemanly figure, which hims to be quite attractive.
Shū is a friendly and thoughtful person who has a playful side to him, owing to his puppets and ventriloquism skills. According to Reiji Kiriya, Shu was constantly sad and fatigued with having to deal with his wife. Because of his unhappy marriage, Shu was ready to take risks with his affair with Hina Tachibana. Unfortunately, he has been indecisive on ending the marriage for some time.
When he noticed that Natsuo Fujii was in love with her as well, Shū was a bit vexed, but nonetheless let Hina choose between him or Natsuo.
Shū was Hina Tachibana's high school science teacher. After noticing how sad and alone she was, he used puppets and ventriloquism to cheer her up. Over time, they developed a close, friendly student-teacher bond.
Years later, Hina crossed paths with Shū again in her fourth year of college where they rekindled their friendship, and eventually, became romantically involved. However, during this time, Shū was married to a daughter of a professor whom he was indebted to. According to Reiji Kiriya, the marriage was full of turmoil because of Shū's wife being insufferable and controlling, which led Shū to pursue an affair with hopes of getting divorced, although he has been suffering from lingering indecision to do so, straining his relationship with Hina.
- The name Shū means "holly olive" (柊).
- Shū's surname Hagiwara means "bush clover" (萩) (hagi) and "field, plain" (原) (wara).