Teacher-student relationships are a common theme in manga. I admit that I enjoy reading manga that has teacher-student romance, even though it’s kind of creepy and possibly illegal in real life, not to mention highly unrealistic… at least based on my high school life. We had no young, good-looking teachers in my school, lol. Most of the manga that I’ve encountered so far involve a high school girl (usually 16 -18 year old) and a young teacher or student teacher (23 – 25 years old)… the age gap in these cases doesn’t bother me… in manga, of course, but in real life, I would find it a little creepy. Yes, it’s hypocritical, lol. Most of the time, the teacher holds off on physical intimacy, except for kissing, until the student graduates from high school, which makes for a lot of sexual tension/longing in the story, keeping it interesting… pretty unrealistic in real life though, which is why I like these kinds of stories in manga.