Clock Zero: Shuuen no Ichibyou Portable

Nadeshiko Kurou is twelve years old, from a wealthy family, and studying at an elite school alongside her childhood friend. She hopes to become a doctor. Every night she dreams of a different world — a ruin-filled place where she is ten years older and everything familiar is gone. When a transfer student named Takato Kaido arrives in her class, she finds herself drawn into an after-school club called Clock Zero. The dreams and the club are not unrelated.