I've had no experience with them, but they make ultralight underwear that has a reputation for being both cheap and good quality. I researched them pretty extensively a while back, and the only reason that I didn't buy any was because they were on back order for so long that I ended out going with something that is a bit lighter but much more expensive.
Note: they are a Japanese company, I believe, and they use Japanese sizing, which is a bit smaller than USA sizing. If you are on the border of sizes, make sure to check out the relative fit of the item that you are considering before placing your order. Also, they seemed to have very knowledgeable people. They have a toll free number, and the people that I spoke to knew their products. They have some brick and mortar stores in the USA, if you happen to be lucky enough to live near one.