I picked up this secondhand kyusu. The seller didn't have any information about it. Based on this link I found elsewhere on teachat (http://www.tokoname.or.jp/teapot/stamp/) I think the artist is Kosho Matsushima.
Unfortunately I have not been able to find any information about this artist. Does anyone know anything at all? Whether he/she is still alive or active? I would love to know more about my teapot, when it was made, and who made it. Thanks in advance!