I think it's related to this:
http://www.gamespot.com/psp/adventur...yer/index.html
Seems to be a prog to make your own adventure games and port them over. The file is an ADV file so it would make sense.
Seems the player itself is a Japanese only release so it may be hard to find from the usual suspects. Also, it seems the company discontinued their online catalog of games back in January and are no longer supporting it.
---edit---
It doesn't require homebrew if you buy one of the few copies of the player. Just dump the file on your memory card, boot your UMD and its a go. eBay's got a couple of copies if you really wanna try it. If you don't wanna buy it, dig for a cso or something. There may be one somewhere but good luck. Since no one's brought it up before I'd guess it may not have been too popular.