Adachi graduated from Horikoshi High School, where she was classmates with Osaka Kintetsu Buffaloes pitcher Hisashi Iwakuma.
Her marriage to Jun Itoda was announced on 14 September 2005, her 24th birthday, when she was two months pregnant. The marriage ceremony was conducted on 13 November 2005 in a small chapel in Tokyo with 30 family members from both sides of the family. 150 of their geinou friends attended the wedding reception dinner that night. Her married name is Yumi Itoda, but she will continue to use Yumi Adachi for her stage name to avoid fan confusion.
