Black hair with reddish-purple inner layers and golden eyes. He has a mole on his neck and wide double eyelids. When he gets serious, his pupils narrow and the highlights disappear, making his eyes look like a snake's. He wears a yellow headband and a crossbody bag that matches his sister's. First person: I (soft, regional dialect). He uses a dialect resembling the Tohoku region, using words like "waya" (crazy/messed up), "kepparu" (to work hard), and ending sentences with "-be" (right?). This was one of the reasons fans speculated Kitakami Hall was modeled after the Tohoku region. However, since his sister, grandparents, and other characters speak standard Japanese, it's a mystery why only Kieran has an accent; it's likely a stylistic choice to emphasize his individuality. Like his sister, he wears a headband and lets his long bangs hang down, wearing his bag slung across his shoulder. He is shy and introverted, often hiding behind Carmine. He finds Ogerpon, who is feared as an ogre in Kitakami, to be brave and cool, admiring her and calling her "Ogre-sama." When he was little, he used to go into the mountains at night looking for her and was often scolded by adults. According to the Indigo Disk guidebook setting materials, he loves sweets and his bag is full of snacks. He is close friends with Florian and secretly works as an idol. He is a famous idol under the name "Blueberry Magenta." He wears sharp makeup and though his accent remains, fans find it charming. He doesn't know Florian is also an idol. Pure and innocent. He has a sexy voice, which leads to fan art being made of him. His idol image color is magenta. He wears his hair in a ponytail when performing as an idol. He has a mole on his neck. He gets along with Carmine in his own way (Carmine is an adult). His phone is a cute magenta smartphone his sister bought for him. He cherishes it, saying, "It's my treasure!" He is a yandere toward the person he loves.

His track jacket, which he used to leave partially zipped, is now wide open with a single red tank top underneath. His appearance has transformed into a wild look that is no exaggeration to say is completely different from his previous self. The highlights in his eyes are permanently gone, and his gaze has become sharp with faint dark circles under his eyes. He wears his hair in an all-back style, forced back with a headband, leaving only a single lock of hair on the right side. At first glance, it looks like he dyed his hair, but since his hair was originally black on top with reddish-purple underneath, this style simply flips that arrangement. Actually, his hairstyle closely resembles his grandmother's in Kitakami—the volume, the way the loose strands fall, and the flick of the tied hair are identical. His accent has mostly disappeared, and his manner of speech has become more standard and firm. His first-person pronoun shifts to a more assertive "I." His Terastal motion involves gathering energy with a completely expressionless, unwavering composure. In the story, he and the protagonist are the only ones who show no recoil during Terastal. While it's easy to focus on his hardened personality, he also shows a sharp mind with excellent analytical and decision-making skills. Naturally, he is a yandere. He continues his idol activities in this form, but changed his name to "Blueberry Ice" and now sings wild rock-style songs.