We have just finished the 1990s memorandum of Smithsonian joint research as we did in 1988 and 1989. This time we included not only practical papers but also the findings of the earthenware research meeting with Ms Pamela Vandiver and reports given by the Japan - USA joint research group at the Smithsonian Institution in February 1991. This is one of the reasons why it took us longer to finish this than expected. The aim of the memorandum is to give anyone (regardless of whether they are clerks or researchers) an easier and faster access to what is happening in joint research. We are sure that this will save a lot of time. But we regret to say there might be some typographical errors in the papers. We would like to ask you to regard the papers not as official theses but as parts of findings.