Nagasaki is located on the Western side of Kyushu island and is a historical location. There you will find the Peace Park and the Atomic Bomb Museum.
Nagasaki is heavily influenced by traders and Western culture as it was the only designated trading location that allowed foreigners in Japan during the Edo period.
They conducted these trades at Dejima island, which is a popular tourist attraction now. In the surrounding areas you can see western influenced houses as well as a famous Catholic Cathedral.
While you are in Nagasaki be sure to try their famous castella cake!