Crossover anime, starting with Hachiman Hikigaya replacing Subaru Natsuki!

A parallel Earth is about to be invaded, and Ji-gu is pulled in to be the savior. But upon closer inspection, she realizes that it is just an ordinary Blue Sun world, and she is powerless to do anything about it.
Then it suddenly dawned on me that several of the male protagonists in these slice-of-life youth stories could become sons-in-law.
Strange and bizarre videos spanning various worlds began playing on Earth and in different alternate worlds.
Hachiman Hikigaya: "I will protect you forever, Emilia—you are the one I have been searching for!"
Ayanokoji Kiyotaka: "Choose one, this stick or that stick?" Shirogane Miyuki: "Your fate cannot conceal your sins."