What’s the name of this dish?

We just came back from our first trip to Japan. We did buy bentos many times and since my boyfriend is not so into seafood he chose the meat option. It had a layer of rice and on top of it thin slices of meat and some dark and little bit transparent sauce with sesame seeds. The problem is that we don't know the name of the dish and I'd love to try to make it myself and surprise him. Does somebody here recognize the dish from the description? :) Thank you very much in advance!

Gyudon? http://en.wikipedia.org/wiki/Gy%C5%ABdon

Actually, it looked like this. http://www.flickr.com/photos/necornboard/5934079532/
Not sure if it's Gyudon. :)

It looks like a version of "gyuudon".

I think It's Gyu-Karubi-yaki bento of 7/11.
http://www.sej.co.jp/products/kodawaribento.html
(Top left)

I agree with xexstyle. Gyudon is a cuisine of a kind of stew beef.
The photo looks like broiled beef with sauce. It's a kind of Teriyaki.

I agree with xexstyle.
Itis Sometimes called just "Yakuniku bento".

And the clues are Yakiniku, Yakiniku-don, Yakiniku-bento, Karubi, Karubi-don, Karubi-dento.