Rin Kobari, known as Kobarin, is Tokyo's 13-year-old magical girl. Standing 154.0 cm tall, she possesses long dark hair, brown eyes, and wears glasses, reflecting a conservative style shaped by her traditional Japanese upbringing. This background instills a lady-like demeanor and strong sense of responsibility. She willingly embraced the magical girl role after meeting her timid shikigami companion, Mosuke, living with him ever since. Her dedication arises from an inability to tolerate the suffering caused by Magatsuhi, persisting despite her own fears in battle.

Her lance-type magical weapon, Petit Bon Heur, incorporates design motifs from Tokyo landmarks like the Tokyo Sky Tree and local flora such as the bladder-cherry. Her costume features distinct Tokyo elements: ginkgo biloba leaves on the sleeves, a floral kanzashi hair ornament, Edo-kiriko glass ornaments, and the Tokyo seal on her sash. A key ability, "Leyline Boost," allows her to amplify her power using Tokyo's leylines, activated by the incantation: "Gods of the heavens, gods of this land. Serve the Emperor. So that all the universe may prosper eternally!"

Rin experiences recurring dreams of battling a mysterious girl, whom she later encounters in Tokyo's Ginza district. Ignoring Mosuke's warnings, she pursues this figure, revealed as Rei Amagiri, another magical girl representing Tokyo with antagonistic intentions. During their conflict at the leyline-rich Tokyo Tower, targeted by Magatsuhi forces, Rin hesitates to attack Rei aggressively, struggling to reconcile duty with reluctance to harm a fellow magical girl across a four-episode arc focusing on her internal conflict and growth.

She resides with her grandmother, embodying the role of an obedient grandchild. Her favorite food is anmitsu.