In the 1950s when U.S. servicemen were based in Japan, Naoko meets a navy officer and they soon fall in love. Naoko arranges for the sailor to meet her parents, but her family are set on her marrying Satoshi who is from a respectable Japanese family. Marrying a gaijin would bring shame on the household. Decades later, when Tori’s father is on his deathbed back in the U.S., he hands her a letter addressed to Naoko that mentions their daughter. This note, and stories her father told her in childhood from his time in Japan, send Tori on a journey to Japan in search of a sister.