On Wikipedia https://en.wikipedia.org/wiki/Saito_Kinen_Orchestra
Creation 1984
Participants Seiji Ozawa - Conductor from 1992
Kazuyoshi Akiyama - Conductor from 1984
City Matsumoto, Nagano Prefecture, Japan
Country Japan

The Saito Kinen Orchestra is one of Japan's most famous symphony orchestras and one of the most prestigious festival orchestras in the world. Its name means "Saito Memorial Orchestra." It memorializes the great Japanese music teacher and conductor Hideo Saito (1902-1974). […]

His best known pupil is Seiji Ozawa (b. 1935). […] In 1984, Ozawa and fellow Saito conducting student Kazuyoshi Akiyama organized a special concert to mark the tenth anniversary of Saito's death. They assembled over a hundred of his graduates into an ensemble for the event, calling the group the Saito Kinen Orchestra. It gave acclaimed concerts in Tokyo and Osaka.

[…] They gathered Saito students again--many of whom had jobs in some of the world's great orchestras--for concerts in Vienna, Berlin, London, Paris, and Frankfurt in 1987. Demand for their return after these outstanding concerts was so great that they assembled again in 1989. […] In 1990, they again gathered to play at Europe's leading summer music event, the Salzburg Festival. They were also invited to perform in the BBC Proms Concerts in London, the Edinburgh Festival, and the Schleswig Holstein Festival. In 1991, they again convened for the festival season, opening the London Japan Festival and traveling on to Düsseldorf, Amsterdam, and New York […].

It was clear that the summer gathering of the Saito Kinen Orchestra was becoming an annual occurrence. Yet continued emphasis on European performances contradicted the main contribution of Saito's life: sowing the seeds of Western music in Japan. The orchestra agreed that the orchestra should emphasize Japan through an annual music festival. Ozawa was appointed its music director. Under his leadership, the Saito Kinen Festival was established in 1992 in the city of Mastumoto in Nagoya Prefecture in August and September […]. The Saito Kinen Orchestra's concerts and opera performances are the two mainstays of the ten-day festivals, which have been held in Matsumoto in late summer each year ever since, still under Ozawa's leadership.

The Saito Kinen Orchestra's membership continues to comprise some of the world's leading solo performers, orchestral principal players, leading chamber musicians, and instrumental teachers. Their shared legacy as students of (or in some cases students of students of) Hideo Saito gives them common ground from which they create an orchestra of great cohesion and tradition despite gathering only for two or three weeks each year. AllMusic