The anime is The Disastrous Life of Saiki K
Basically Shun (blue guy) thinks that the Dark Reunion, "are trying to steal "Black Beat" a dark force that dwells in the latter's right arm and create a new world with it." (fandom.com)
I also believe Disatrous Life of Saiki K characters show up non sequiturially as a form of fandom gone awry.
eg. "I love DBZ, I'm going to draw them and not really pay attention to the story"