Mancio Itō was born as the grandson of Yoshisuke Itō, the landed daimyo of Hyuga Province. He was introduced to Christianity while he was living in Bungo, and by this chance, he entered Seminario (Seminary) in Arima, intending to become a priest. 

 

In 1582, when three of the Christian daimyo of Kyushu Omura, Otomo, and Arima, dispatched a group of four youths on a mission to the Pope and the king of Spain, he was chosen by Otomo Sorin to be one of them, and though he was only thirteen years old at the time, he acted as spokesman for the group.

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It is recorded that Mancio danced with Bianca Cappello, the queen of the Grand Duke of Tuscany when the envoy was invited to a ball in the Grand Duchy of Tuscany where they visited on their journey to Europe.

 

In Rome, he was made an honorary citizen and raised to the rank of the nobility with the title Cavaliere di Speron d'Or. The group returned to Nagasaki in 1590, and the following year Ito was summoned to an audience with Hideyoshi Toyotomi and gave an account of what he had seen and heard in Europe. Hideyoshi took a liking to them, and he especially recommended Mancio to become an officer, but Mancio declined since he had made up his mind to become a priest.

 

The same year he entered the novitiate at Amakusa in Kyushu, becoming a member of the Jesuit order. During the period around 1606-07 he assisted in giving instruction at a seminary sponsored by the Arima family, and later became a regular member of the priesthood. He taught at a collegio in Nagasaki but died of illness on November 13, 1612. It was 22 years after he returned from Europe.