Aoki Imported Bonsai tree soil blend is well-known and well-loved in Japan. The blend is Akadama, Fuji & Kiryu soils. All three are of volcanic origin.The grain in the Shohin Aoki mix are very small (3mm) and are particularly suited to small trees, though some people use this mix for larger trees and even for older specimen quality trees.
This is our first year carrying Aoki mixes, so we have no personal experience with them, but we hear good things from other bonsai growers.
1 gallon bag, Very small Shohin grain (3mm)