Tetsuro Kitahara completed his PhD in March. The title of his thesis is: "Computational Musical Instrument Recognition and its Application to Content-based Music Information Retrieval" (PDF). It's in English! (It's the first Japanese MIR related thesis written in English which I'm aware of.) He wrote it while working at Okuno's Laboratory at Kyoto University. He has now joined CrestMuse (an English version of the project web page is on its way) as postdoc at Kwansei Gakuin University (Katayose's Laboratory). I saw one of his demonstrations last year and was quite impressed.
(The list of MIR related PhD theses and dissertations has been updated.)