Matsuri tried to listen to the Fandead mourn Rushia.
https://youtube.com/watch?v=WKyBvuvnuJoMatsuri showed up there because she forgot her profile would shoot to the top of the viewer list.
She was there in Fandead's mourning space to listen to them cry.
Remember Matsuri has repeatedly said that she likes seeing men in despair. She likes seeing men in physical and emotional pain. That's literally one of her biggest fetishes.
Remember Matsuri had a giant menhera fit when Haachama ignored her request to show up for her birthday live, but ended up appearing in Rushia's 3D live.
There's a very real possibility Matsuri was the senpai that bullied Rushia.
