The Amusement Club is cleaning the club room in preparation for new students and perhaps new members.  Opening a mysterious closet they discover a device that sends Akari back in time, with she takes as a chance 

to fix her mistakes.
If you change the past,
Si cambias el pasado, entonces cambiarán 
todos los recuerdos que has tenido en este año.
Si alteras el pasado, entonces puede que cambien todos los recuerdos que has ido haciendo durante este año.
Se você mudar o passado,