I was at an old computer, trying to find information on the Internet about a character that was either named Maria Moriya, Marie Mariya or even Maria Mariya for all I know. I will refer to her as M.M. for making the writing and also the reading a bit easier. (To add another bit of clarification, yes this name was definitely taken from the main character of Higanbana no Saku Yoru Ni, but a few letters were off.)
From my search, I found two noteworthy things. One was a YouTube video about a Yume Nikki fangame titled after her and presumably starring her, it had a thumbnail showcasing the character (which was too small to see ) in a world similar in appearance to the Crystal Caves from Yume 2kki, with large pink crystals for walls and a dark purple semi-transparent floor which also showcased the dark backdrop of the world.
The other thing was a news article from a seemingly very, very old website, it was all in 4:3 and probably ran in Flash (which could explain why it remained like that for so long?), it also all featured a very wintery aesthetic for some reason with a particular gif of an angry ASCII snowman being plastered all over the place (perhaps the article was released around Christmas?), every navigation button had a transition from left to right of snow covering the screen and then changing to the next page.
Doing some more digging on the winterland vista I just discovered, I found the face of the boyfriend from friday night funkin' in what was presumably a flash game on the site since it seemed to be positioned like a life icon, I ONLY remember this bit because I distinctly remember being like, oh shoot! the dev ripped this off! but sadly it was just in my dream. Regardless, this was a fairly odd and irrelevant interlude within the same dream.
I click on a logo on the corner of the page and am redirected to a contemporary version of the site with articles relating to the present (they were displayed like a forum?). I did not think too much of it, so I headed back to my winter wonderland.
There, I find an article about a creepypasta about what seemed to be a NEET travelling through computers, to put it short he he hated the world and everyone in it so he acquired that supernatural ability somehow and went on to took his revenge. I could see a vision of him typing angrily at his computer writing rant after rant in a dark bedroom with various old cartoon characters on the bed near him. The angle he was viewed from constantly switched and the characters in the back did with it too, was he jealous on cartoons too? He also had the voice of Billy from The Grim Adventues of Billy and Mandy. Hoooow odddddd.
With this, I forgot to mention the actual article I found, it was about a woman that shared M.M.'s name being murdered with no known culprit or cause.
For the sake of a conclusion, I will assume the NEET person was the one who murdered the woman, released a manifesto of sorts, hence the typing sequence I witnessed, and mysteriously disappeared with no traces left. Avid occult writers then wrote an interpretation of the manifesto (no idea how they could've gotten it though, assuming it was not released) which ended up reading like a creepypasta, which turned into an obscure urban legend.