Tokei Jikake no Etranger

Aki and Mikoto Tachihara are cousins and they attend the same middle school. Aki is a bad student and relies a lot on Mikoto, while harbouring a secret crush for him. One day, after a mysterious dream, she finds an unknown girl in her bedroom: her name is Nao, and seems to come... from 25 years ago?!

Note: Includes the one shots "Pearl no Kimochi" (パールの気持ち) and "Himawari no Illusion" (ひまわりのイリュージョン)