Sumire Shinohara is Licca Kayama's best friend, maintaining a close and supportive bond throughout their shared experiences. She attends the same elementary school as Licca and belongs to her core friend group alongside Dai Takabayashi and Tomonori Michitani. Sumire harbors a romantic interest in Dai, who remains largely unaware due to his preoccupation with Licca. This dynamic does not disrupt their friendship, as Sumire continues positive interactions with both Licca and Dai.

In the series' second half, Sumire gains a significant protective role for Licca after receiving the green Calling Ring bracelet. This item allows her to summon the warrior Doll Izumi, one of the three Doll Knights defending the royal family of the Doll Kingdom. Sumire becomes Doll Izumi's primary summoner, using the transformation spell "Fururu Furora Gurine Guraine" to activate her when needed.

Characterized as romantic and sensitive, Sumire often imagines elaborate romantic scenarios involving Dai. She displays timidity fitting the "Shrinking Violet" archetype but demonstrates moments of bravery when her friends are endangered, aligning with the "Cowardly Lion" trope. Academically responsible and a good student, her dark hair and studious nature match the "Brainy Brunette" description. Her personality contrasts with Licca's energetic demeanor, as Sumire is more reserved and graceful.

During events involving the witch Dana's reawakening at an amusement park, Sumire is present with Licca, Dai, and others. She participates in the group's efforts to confront threats, supported by the Doll Knights' protection.

Sumire's loyalty to Licca remains unwavering. She consistently prioritizes their friendship despite the complexities of her unrequited feelings for Dai. Her role evolves from supportive friend to active participant in Licca's protection through her connection to Doll Izumi.