Yamaguchi (山口亮子) was a colonel for the Towada Self-Defense Force (TSDF). Prior to becoming a ranked officer, she was enrolled in the TSDF High Technical School. Once there, Ryoko does everything she can within her own ability to get in the fast-track to Officer Training. While there, her instructors along with superior officers were impressed with her fortitude to strive to be best as well as her phenomenal leadership skills and toughness on the battlefield. Which as able to helped her be a viable candidate for the fast-track officer training. After serving several years in the military she resigned and joined the United Mercenary Association (UMA) as a mercenary. She is one top ranking colonels in UMA and she is the leader of Team Blue which consist of Maj. Alina Novikov, Maj. Zara Moussa, 1st Lt. Felicia Castro and 1st Lt. Marsha Thompson.