...The Bandana? Yeah, you're supposed to find that on B16F, in Middle-West Portion of the sand maze. If you hear a ghost, then I think you've already found the spot and can turn it in.
If not, From the stairs down, Backtrack. Once you've teleported to the other side, take the sand dunes to the left. That's the only moving sand you should cross, because if you head just south from there, along the edge should be the location you need to check.
Edit: Derp. You've already found it.
Do you suppose he's passed on now that someone found that silly thing?
Maybe. I didn't even know EO supported 'ghosts'. But now that I think about it, the 4th Stratum is a lovely place for ghosts. Especially at night. It's cramped. Trees attack you. Creepy, medusa based trees. And it's a wasteland.
That was kinda creepy though.
You hear a voice but nobody's there... and that's it. The end. -.-
I actually searched the floor once more after finding the bandana, thinking the guy was lost or something. I was thinking maybe it has a 'best ending' or something. Or maybe the guy would magically show up and say "Oh you found my lost bandana!" or something.
Quests like these leave a bad taste in my mouth for some reason.
...or maybe he'll haunt his lover now, since she has his rainbow bandana.