Toshio Ban joined Tezuka Productions in 1974 as one of Tezuka's assistants. After working for a period as a free-lancer, he later re-joined Tezuka Productions in 1978 as the sub-chief of manga production for magazines, supporting Tezuka's creative work until the end.
From his Comiclopedia page:
As the artist who worked so closely with the master, he made a 900 pages manga biography, called 'The Osamu Tezuka Story: A Life in Manga and Anime' (2016). Besides the life and work of the creator of 'Astro Boy', 'Kimba the White Lion' and 'Black Jack', the book also gives an anecdotal study of the evolution of Japan's early manga and anime business.
Toshio Ban has also worked with writer Peter Tasker on a futuristic manga story called 'I am a Digital Cat: A Japanese Future' (2012).