The Equinox is a triathlon racer from TREK, a company with superior carbon material technology and TREK has won many races, including the Tour de France, and the Equinox is a triathlon racer from TREK. It is an all-rounder with excellent aero performance and stability at high speeds, as well as a ride and performance similar to the company's general road racers, even off the flat.

Otonokizaka Gakuin, a traditional school located between Akihabara, Kanda and Jimbocho, is on the verge of consolidation. Nine girls, led by second-year student Kosaka Honoka, rise up to meet the school's crisis. What we can do to protect our favourite school. ...... That is to become an idol! Become an idol to publicise the school to the world and increase enrolments! This is where the girls' 'story of making it happen together' School Idol Project began!

Third year at Otonokizaka Academy. She is the student council president at Otonokizaka Academy and a dance coach for μ's. She grew up in Russia, the home of ballet, and was educated as a gifted ballet dancer from an early age. Her dancing ability is at a professional level. At first Eri was sceptical about Honoka Kousaka's plan to increase the number of applicants to Otonokizaka Gakuin and prevent the consolidation of Otonokizaka Gakuin through the publicity effect of School Idol, but she was inspired by Honoka's enthusiasm and joined the group herself as a member of μ's. She was also inspired by Honoka's enthusiasm and decided to join as a member of μ's herself. Her grandmother is Russian and she is fluent in Russian. Her habit is to say "Harasho" in Russian.