It may have been apart of an anthology or collection of one shots.
I believe it was a shounen ai, not a yaoi, but it's been a long time since I've read it so I can't remember.

Anyway, the basic plot is that this prince goes to visit this monastery and seduces a monk while there.
The distinct part about is was the twist at the end, when the monk was shown locked in a room after having been willingly blinded and had his hearing taken as well. The whole thing with this prince was that it was some sort of tradition that before anyone could become king they had to seduce a monk and get them to love/trust/rely upon you so much that they would willingly allow their sight and hearing to be taken away.

Like I said, I'm pretty sure it was from a collection of one-shots, all of them shounen ai or yaoi, and I believe they tended to have some dark twist to them. Or that's how I remember it. In either case if love to read this again, so any help is much appreciated.

Searched up the tags but not sure if this is what you're talking about
http://www.mangaupdates.com/series.html?id=3526