Based on the information Satoru gathered, March 1st 1988 is X-day. The day when Hinazuki will missing because kidnapped. It means Satoru has eleven days to prevent this and change the future. 

But, there is one important thing Satoru should do first. Save Hinazuki from her Mother. Seriously Kayo's mother is really pissing me off, what the fck is she thinking!? abuse her own daughter. Does she has a mental illness?. OMG... hopefully she gets killed!!!.