It seems like he is seeing something that isn't there, perhaps due to stress.

Most of the houses in this area use a cesspool.

My niece is very smart.

That child is really cute, isn't she?

I love the taste of mekabu.

This apple is slightly smaller than usual, isn't it?

This apple is slightly smaller than usual, isn't it?

This shirt is slightly larger than usual, isn't it?

This apple is slightly larger than usual, isn't it?

He was dressed in all black.