Boushiya Ellipsis

Whatever Ozu Hayato was expecting when he went to his late grandfather's house for the reading of the last will and testament, it wasn't for his grandfather's old hat to fall on his head and allow him to see the ghost of a long-dead girl. Nor was it to inherit an entire office building, complete with a members-only hat shop. And who exactly is that man responsible for carrying out the terms of the will, and how does he know about the hat? And what's it all have to do with Hayato, anyway?