Rusk ラスク is a popular sweet snack and omiyage in Japan. It is a sweet twice-baked baguette. I don’t think it is popular or well-known in the US, but for some reason it is really popular here. I see them everywhere, souvenir shops, bakeries, and even the conbini.
It is not anything particularly special, and I have had many types from many places within Japan. They all taste sort of similar– like a very dry, crunchy sweetened baguette slice. It tastes okay, but I don’t really understand the popularity. Most famous is probably the “Gouter de Roi” brand. Recently one of my sensei brought in a “colorful rusk,” which actually has a fruity taste that I kind of like, and the look is rather festive (there were also purple, green, and yellow colors).