I'm of the belief that Yasu is now a successful politician leading the country while still keeping contacts with the SPR. And maybe every now and then he'll "help" the SPR and/or help fellow politicians with paranormal issues of their own. He might also use that to gain support.
though i knew that the neighbour harassed them, i knew something else was happening, considering Mai's intuition is very good. she already felt something was wrong the moment she stepped into the house