While – Manga

“my father also said that as long as you live, there is hope. but then if we come to die … ” luna is optimistic despite her difficult student's life . until she falls from the roof of her university. she wakes up then in a strange and hostile place where the only solution to get out of it seems to be to die repeatedly. why is she here? and what does the entity named y want, whose messages drive her to accept this cycle?