Preface. To commemorate the retirement of Professor Kimitaka Kaga from the Graduate School of Medicine, University of Tokyo.

It is with great pleasure that we present this supplement of ActaOtolaryngologica to commemorate the retirement of Professor Kimitaka Kaga from the Department of Otolaryngology and Head and Neck Surgery of the Graduate School of Medicine, the University of Tokyo, Tokyo, Japan. Professor Kaga was born in 1944 and grew up in Hokkaido, the northern island of Japan. His birth place was Bibai City, which had a well-known coal mine. He graduated from the School of Medicine, University of Tokyo in 1971. After completing two years of training in otolaryngology at the university hospital of Tokyo, he joined the Department of Otorhinolaryngology of Teikyo University in 1973 (Chairman: Professor Jun-ichi Suzuki). He began his training as an otologic surgeon and clinical auditory neurophysiologist. In Teikyo University, he met Professor Tokuro Suzuki, and Professor Robert Galambos who introduced the concept of auditory brainstem responses (ABR). ABR became his very important clinical tool for investigating disorders of the inner ear, brainstem, and auditory cerebral cortices. Professor Yoshikazu Shinoda trained him in auditory and brain science research. He made various new discoveries concerning central auditory disorders as determined on the basis of ABR and neuropathology. Meanwhile, Professor Tetsuo Ishii guided him in the field of temporal bone histopathology. He studied patients with cortical deafness and aphasia together with speech pathologists. Professor Jun-ichi Suzuki trained him in otologic surgery. Since his student days, he was interested in medical education. In 1983, from July to December, he had a wonderful opportunity to study Medical Education at the Center for Research in Medical Education and Health Care of the Jefferson Medical College, under the supervision of Professor Joseph Gonnella, in Philadelphia, USA. From 1984 to 1985, he joined Professor Jeniffer Buchwald’s laboratory of the Brain Research Institute of UCLA in Los Angeles, USA to study in the origins of P300, which is one of the event related potentials. In 1992, Dr. Kaga was appointed to Professor and Chairman of the Department of Otolaryngology, Graduate School of Medicine, University of Tokyo. During his professorship, he introduced new ear surgical techniques, such as total middle ear reconstruction and reconstructive surgery for microtia and atresia developed together with plastic surgeons, and the use of cochlear implants and auditory brainstem implants. During his sixteen years, he accepted and helped to educate 132 freshman doctors and 20 foreign graduate students. In 200