@Athrun0505 I understand there's nothing complicated about it; however, with someone who knows next to nothing on that series, I would have to do my own research, take time to watch the show, and understand the world these characters are in to make a compelling story where those two universes collide.
When I write fanfic, I want to try to be as lore accurate as I can be. Sometimes I will add in stuff to make it feel different and unique. I feel that there is a lot to take in when it comes to Stranger Things and the lore and the powers that people possess. Again, this is coming from someone who doesn't know the series, so while all of that might not be as complicated to those who have watched it, it is new for me and it is something I need to learn.
And I also do not write anything with real people involved, either it be a one-shot with the reader or a series such as an anime crossover like the story you suggested. I feel that since I do not personally know the actor who is portraying the character in the show, I cannot write them to be accurate. I understand that these are fictional characters, but they are played by real people.
So, again, I would definitely struggle to write something like this since it's not in my area of interest and it goes against an area of my comfort zone.