As BLUE SEED VOLUME 4 opens, six year old Yukiko is kidnapped by the Aragami to force her father to release data from the Kushinada Project. Incensed that an innocent has been put in danger because of her, Momiji makes it her personal crusade to rescue Yukiko. The action continues in the second episode when, as a result of her popularity after rescuing Yukiko, Momiji is nominated to perform for the Kanto Pop-Idol Scout Caravan. However, the contest's climatic singing duel, which pits Momiji against Sakura Yamazakim a magic using young lady with an eye on Mamoru, is interrupted by the attack of a ginkgo tree Aragami.