He was one of the most powerful feudal lords of Kyūshū and one of the first to allow trading with Europeans, particularly the Portuguese, through whom he amassed great profits in the import of western firearms.

That same year he became an ally of the powerful wakō leader Wang Zhi, inviting him to live in Hirado and allowing his band to dominate the outlying islands off Kyūshū.

This led to many armed conflicts, including one attempt at taking the Portuguese black ship in the Battle of Fukuda Bay by Takanobu.

This rivalry lasted for over three decades, and long after Takanobu had retired, until Ōmura eventually won out by ceding Nagasaki to the Jesuits in 1580, making it the Portuguese port of call henceforth.

Although initially tolerant to the Kirishitan movement introduced to Japan (Takanobu welcomed Francis Xavier to Hirado in 1550[3] and his retainer Koteda Yasumasa converted to Catholicism in 1551), he expelled the Jesuits from his domain in 1558.