Sophia, once engaged to Japanese diplomat Shintaro Umakai, joined the Russian Spiritual Corps under Grigori Rasputin after his departure from Russia. Rasputin recognized her ability to manipulate Konjiki. Infiltrating the flying battleship Amanohara by feigning amnesia and mental regression to childhood, she acted as a mole for Russian forces. Her mission aimed to sabotage the Lime Unit—a team of girls piloting mecha called Raimu—and manipulate Shintaro into killing them. Sophia piloted a light blue Raimu under the codename "Veludo," referencing velvet fabric as per the series' naming convention.

Her mission ultimately failed. During the final battle, she suffered severe injuries after being crushed by a falling boulder. With her remaining strength, she intercepted an attack from Rasputin's Raimu to protect Shintaro. She died shortly after, expressing a final wish for him to live on. Her actions shifted from antagonism to sacrifice, resolving her personal conflict with Shintaro.