As an influential animator, he played an essential role when two
important directors in Japanese animation, namely
Isao Takahata and
Hayao Miyazaki,
made their theatrical debut. In 1965, when Toei Doga chose Otsuka for
animation director of their tenth feature film, he recommended the
studio to pick out Takahata for director. This tenth feature film
resulted in Takahata's theatrical debut
Taiyô no ôji: Horusu no daibôken (1968). Again in 1979, when
Tokyo Movie Shinsha asked him to make the second "Lupin the Third"
movie, he invited Miyazaki to direct it. This collaboration resulted in
Miyazaki's theatrical debut
Rupan sansei: Kariosutoro no shiro (1979).