In 1570 a powerful landowner or daimyo called Å mura Sumitada became a Catholic ( he chose Bartolomeu as his Christian name ) . He made a deal with the Portuguese to make Nagasaki better for trading . In 1570 daimyo Å mura Sumitada converted to Catholicism ( choosing Bartolomeu as his Christian name ) and made a deal with the Portuguese to develop Nagasaki , and soon the port was open for trade .