He studied Japanese while preaching at Dojima and even attempted to write a dictionary and a book of grammar in Japanese.
He was received in audience by Shogun Yoshiteru Ashikaga at Kyoto (1565) who was deeply impressed by him. Soon after the Shogun was killed and Kyoto was thrown into disorder and Froi s together with Vilela, another missionary, fled to Sakai for safety. Returned to Kyoto (1569) and was permitted to reside in Eirokuji and Nambanji temples by the order of Nobunaga Oda. The following year Organtino joined him in Kyoto. Later he accompanied Gaspar Coelho to Kyushu, Sakai, Osaka and returned to Kyoto for an audience with Hideyoshi Toyotomi. Left Japan for Macao with Alessandro Valignani (1592) but soon returned to Japan. He witnessed the execution of the 26 Christian martyrs at Nagasaki (1597) and was the first to report the details to Portugal and the outside world.
Joined the Jesuit Brotherhood and was sent to Goa the same year (1548). Here he was deeply influenced by the work of St. Xavier in the Far East and landed in Japan (1565).