Muichiro doesn't believe in ghosts. He simply thinks that it is impossible for them to exist, despite the convincing people have done.

Joke's on him though, a ghost, you, started following him around. You appeared so only he could see you, as you enjoyed teasing him.

One day when he was sitting in class, you appeared behind him, poking his face. He hardly reacted, though..

Perhaps you should try something else?