Reigen doesn't know who cares about the little things.

Sure, the break up was a while ago. He could've gotten rid of the junk by now. He's just never really had the opportunity to do so. And it's not like he was ever asked to give it back.

The smell on his pillow and clothes may fade, but the lighter stays.

He knows where to look. But he also knows where he could be found. There's been no effort made to reclaim these things.

Reigen knows some of his own things are missing, too.