In the opera 'Madame Butterfly', what is the name of the naval officer who is the title character's lover?

'Madame Butterfly' is an opera in three acts (originally two) by Giacomo Puccini, with an Italian libretto by Luigi Illica and Giuseppe Giacosa. It is based on the short story "Madame Butterfly" (1898) by John Luther Long, which in turn was based on stories told to Long by his sister Jennie Correll and on the semi-autobiographical 1887 French novel Madame Chrysanthème by Pierre Loti.

In 1904, a U.S. naval officer named Pinkerton rents a house on a hill in Nagasaki, Japan, for himself and his soon-to-be wife, "Butterfly". Her real name is Ciocio-san (pronounced "chocho", the Japanese word for "butterfly). She is a 15-year-old Japanese girl whom he is marrying for convenience, since he intends to leave her once he finds a proper American wife, since Japanese divorce laws are very lax. The wedding is to take place at the house. Butterfly had been so excited to marry an American that she had earlier secretly converted to Christianity. After the wedding ceremony, her uninvited uncle, who has found out about her conversion, comes to the house, curses her and orders all the guests to leave, which they do while renouncing her. Pinkerton and Butterfly sing a love duet and prepare to spend their first night together.