Born in the city of Shuri, Okinawa. At the age of 16 he started to train Karate with Master Sokon "Bushi" Matsumura.
He was a very close friend of Matsumuras uchi deshi, Yasutsune (Ankoh) Azato and was furthermore a student of Shimpan Gusukuma and Yasuri, Iwah's uchi deshi.
He is famous for being instrumental in the introduction of Karate in the public school system curricula. To help the teaching process he developed the Pinan kata basing himself on the advanced Kata like: Kushanku, Passai, Chinto and Jion.
His attainments are very often told to emphasize the high technical level he attained. Gichin Funakoshi refers to his physical strength, his incredible ability to withstand blows and his incredible grip.
Master Funakoshi recounts that neither Master Itosu nor Azato ever bragged fo their "heroic" attainments in karate, they would say that those "crazy things" were to be blamed on their youth.
What is perfectly clear is the fact that he was a master who had innumerable and very important students, many of them created a series of different styles of Karate, even though it was never his intention to have this happen.
One of his most famous students was Gichin Funakoshi, someone that always remembered him throughout his life as a great example of what a great master should be and tried to transmit the teachings he received from him.