Crossover anime, and you call this a slice-of-life story?

Shangguan Yun, the student council president of Shuchiin Academy, originally planned to have a peaceful high school life.
Until—the arrogant heiress of the Shinomiya family tries every means to get him to confess his love, the dead-eyed boy Hachiman Hikigaya is turned into a half-ghoul, the brown-haired elementary school student adopted by the family wants to dissect zombies, and the dragon girl found in the mountains...
I remember that useless angel who only knew how to play games all day and was constantly complained about by the disciplinary committee, and the triangular "unidentified object" floating on the table in the student council room, radiating holy light.
Lightning crackled in Shangguan Yun's hand. "Destroy it."
Kaguya-sama: Love Is War, Oregairu, Saekano, Maid of the Dragon, Gabriel DropOut, Detective Conan, Noragami, etc.