A ghost that can't do ghost stuff is funnier than any ghost that can. Q-tarou's one job is to be a monster living with a normal family, and he fails at it constantly in the most lovable way possible. Every episode is him crashing through their lives, breaking the rules of what monsters are supposed to be, and somehow making that the whole point. This is comedy built on a single perfect premise that never needs to get bigger or sadder to work. If you watch anime for the warmth of a character who belongs nowhere and fits everywhere anyway, this is it.
Q-taro is a monster who lives with the Ohara family. He can fly and turn his body transparent, but unlike other monsters he has no ability to change into other things. He is scatterbrained, so he is always making mistakes and stirring up trouble for the people around him. The result is a TV comedy built around his clumsy blunders and the mischief that follows him through everyday life.