Detective Satan

A 5 year old boy wakes up after having a weird dream. Remembering that he was going to meet someone, he heads out to the streets of New York. He arrives at an old cafe, which had glass doors and windows. He stood outside the cafe, waiting for the person he was supposed to meet. After waiting for a few minutes, he saw a girl wave towards him while running towards him. He was standing close to the cafe and as the girl got closer to the cafe, the doors and windows of the cafe exploded, sending a shockwave and heat wave. It was enough to send both their tiny bodies flying. The boy, who was supposed to start crying like any other kid, looked around to find his friend. He dragged himself towards her, ignoring the pain from the bruises and the cuts from the glass shards. As he crawled through the cafe, he felt his pain slowly decrease and his body started gaining strength. By the time he got closer to the girl, he could already stand. He looked down at his wounds, that healed at a visible rate. Although he had many questions in his head, he dismissed all those thoughts as he had an unconscious girl before him. So, he looked around, to find someone to ask for help, among the panicked crowd that was running from the cafe. That's when he saw them for the first time, dressed in black suit, a black coat, a black hat and black glasses. They looked like men, with a very skinny body. (If you still don't feel interested to read it, go ahead and read 2-3 chapters to give it a try.) Note:- 1. There are different worlds he will travel to, but the ones I have in my mind are MHA, One Piece and Naruto. He is currently in the world of Detective Conan. 2. I wanted to write about a multiverse traveller that doesn't know the future through manga or shows. They became very boring. I don't know if anyone has tried this before, but I think it might be great. 3. MC has powers, which he will slowly discover and harvest. My MC looks like Shallott from DBL. I needed a character with black hair and decided to go with him. 4. This will be a harem and it cannot be avoided with his powers. Those who don't like it, can leave before. 5. I will be writing the whole story in the MC's POV.