Transmigrated into a Book and Became a Spoiled Antagonist - Chapter 5

Thirty-three classmates hold a reunion after graduating. Tensions soar and old friendships are tested, as a strange turn of events lead them to follow the path of the ancient gods.

Su Yuan transmigrated to Teyvat.At the same time, another strange and eerie force descended upon this world.The entire Teyvat was affected to varying degrees.Furina endured five hundred years of loneliness in order to save Fontaine.But just before the dawn of victory, she succumbed to madness under the influence of the eerie force...“No one understands my loneliness... No one can comprehend my fear... No one can listen to my pain...”“Why must I give so selflessly... Do the people of Fontaine truly deserve my sacrifice?”

A side story series featuring the girls of Kyoukai Senjou no Horizon.

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates