As the principal investigator and project leader of the TAMA project, Dr. Kozai had made a significant contribution to the realization of TAMA300. The TAMA project, which was hosted by NAOJ, was promoted through collaborative research among many gravitational wave scientists across Japan. After construction of TAMA300, the laser interferometer gravitational wave detector, within the Mitaka campus of NAOJ, the project had obtained more than 1000hrs of continuous observation data from its stable long-term operation with the best sensitivity in the world at its time. The achievements and experience gained through TAMA300 has been passed on to a new generation of scientists who are now leading the realization of KAGRA.

During many different phases of its implementation, the TAMA project faced various challenges, including financial hardships which required understanding and support from a wide range of people. Dr. Kozai's personal connections and recognition proved to be of great help to overcome each of these crises.

Dr. Kozai was always happy to hear about the accomplishments and advancement made by the young scientists and graduate students who had participated in TAMA300, and had high expectations for their future success.

Moreover, Dr. Kozai was one of the original members of the Gravitational Wave International Committee: GWIC, and had shown great interest and understanding in not only promotion of international technological exchanges, but also in international network of observation and data analysis. He had continued to support and hold high expectations for KAGRA, the successor of TAMA300, and while being pleased with the first observation of gravitational waves and the advancement in gravitational wave astronomy thereafter, showed some regret that the realization of KAGRA could not be made in time.

With our deepest condolences and sympathies,

The Gravitational Wave Project Office, NAOJ