千菓子 higashi: dry wagashi, dry sweets (no or little moisture so they stay good longer). This is the generic term, which can include a few different types (including rakugan 落雁 used for Obon offerings). These are the opposite of namagashi which are made fresh and have a lot of moisture content.
和三盆 wasanbon: a type of Japanese fine grain sugar used to make wagashi. This term is also used for the small sugary shapes that are served with tea melt in your mouth.
I visited a shop here in Naha called 知念製菓 和菓子 四季彩 Chinenseika Wagashi Shikisai. The kanji 製菓 seika means confectionary, and 和菓子 wagashi means Japanese sweets. I wanted to pick out some cute confections to serve with tea sometime. The shapes and colors are often seasonal, with a few year-round standbys. These sweets are basically just pure sugar with some added color, contrasting perfectly with the bitterness in tea. If you buy them individually, each little sweet is 70yen at this shop (though if you buy a bag of the same shapes, you save money on the per piece price). I like variety and did not need many, so I chose a few individually that I liked.