Ren Kitahara is a male student at Ayanagi Gakuen High School Division and a member of Team Sazanami alongside Nanjo Koki. He possesses auburn hair and green eyes, standing 176 cm tall with a birthday on April 22 and blood type B.

Personality-wise, he displays impulsive tendencies, often necessitating Nanjo's intervention to restore composure. This creates a contrasting dynamic where Nanjo acts as his stabilizing counterpart. During their second year, Nanjo notes Kitahara's gradual shift toward greater seriousness.

In the Halloween OVA, he engages in pumpkin decorating, cooking, and Halloween traditions after receiving pumpkins from Futaba and Saotome. He performs "Pumpkin Mate♪" with Hoshitani Yuta, Tatsumi Rui, and Ageha Riku, then joins Nanjo Koki, Ageha Riku, and Hachiya So for "Storytellers" and "Gift ～Ageha x Hachiya x Kitahara x Nanjo Ver.～". His musical repertoire also includes the duet "REFLECTION" with Nanjo Koki.