AppExTrade is Japanese Cross-Promotion Platform for only game apps.
PocketGamer.biz introduce us here http://www.pocketgamer.biz/r/PG.Biz/Zucks+news/news.asp?c=53196
They say"Similar to the likes of Chartboost and AppFlood in the west, it's a Japanese-focused cross-promotion platform, offering free cross-promotion (both internal and external), and a non-incentivised install/user acquisition network."