Emi Kojima serves as an alias for Septem, a being from Evergreen's magical realm. She assumes this human identity upon transferring to Chihaya Hiiragi's school, maintaining the guise as earthly cover. Septem journeys to Earth with Bergamot, Chihaya's father, to shield Chihaya from adversaries Fennel and Calendula. Bergamot recruited Septem after stealing hazardous seeds from Evergreen, prioritizing his daughter's safety. Unrequited love defines Septem's feelings toward Bergamot, who fixates on her due to her resemblance to his late wife, Emi Hiiragi—Chihaya's mother.

Adaptations diverge in her portrayal. The non-hentai television anime depicts Septem heroically aligned with Bergamot against Fennel and Calendula, consistently aiding Chihaya's protection and seed retrieval. Conversely, the original hentai OVA casts her as a villainess directly serving Fennel and Calendula against Chihaya, including a scene where she claims to be Chihaya's biological mother.

Physically, Septem exhibits violet ankle-length hair, garnet eyes, and frequently wears a tiara. She features across media: the four-episode hentai OVA series (2000-2001), the two-episode "Palpitating Summer Camp" OVA (2002-2003), and the non-hentai television anime "Magical Canan" (2005). The "Palpitating Summer Camp" OVAs include her without significant character development.