Seiko Rikiishi is the inaugural recruit of the Miko Council, a team dedicated to thwarting supernatural dangers. Bubbling with enthusiasm, she masks her inexperience by affectating worldly savvy, particularly in romantic matters—a façade frequently undermined by comically disastrous encounters with boys. Her weapon of choice is a sacred spear, channeled through her "brave girl spear" technique. This attack’s name becomes a recurring joke when a teammate mishears it as "brave spear girl," injecting humor into battles. Initially reluctant to vocally declare her moves mid-combat, she eventually leans into the habit, signaling her growing confidence within the group.

A pivotal subplot involves a love letter she interprets earnestly, her gullible optimism blinding her to the impending farce—an incident emblematic of her endearing, if impractical, idealism. Female classmates swiftly form a fan club in her honor, though its operations remain peripheral to her story. Her arc centers on embracing her shrine-maiden duties while integrating her vibrant idiosyncrasies, evolving from an eager novice into a self-assured guardian who melds personal flair with ceremonial responsibility.