The teacher being here in the manga might be part of a planned storyline. It could be to introduce a conflict, provide support to the main characters, or to drive the plot forward in an unexpected way.
Well, unfortunately, there are always some individuals who have distorted minds and produce such adult-oriented comics based on popular titles. It's a sign of their lack of proper values and creativity.
The manga's popularity stems from a combination of factors. The art style is appealing, the plot has unexpected twists, and it offers a fresh take on the student-teacher dynamic. Also, it manages to balance comedy and drama effectively.
The 'Why the Hell Are You Here, Teacher!' comic is popular because it combines comedy and romance in an unexpected way. The characters have great chemistry and the situations they find themselves in are both amusing and relatable. Also, the author's storytelling skills make it a page-turner.
It could be a creative decision by the publishers or the artist. Coloring the manga might add depth and detail to the characters and settings, making it stand out in the market.