Kanna Kuroda serves as the protagonist's best friend and primary strategic advisor. She sports short pink hair, blue eyes, and typically wears a white shirt with pink stripes, pink shorts, long black socks, and a blue jacket featuring a dog-shaped hood. Her personality blends seriousness and helpfulness with deep analysis, though she exhibits moments of high excitability. Despite holding extensive expertise in the card game system and mechanics, she cannot battle personally due to information overload during matches.

Originating from a village whose stadium faced jeopardy, she recruited the protagonist through a test battle to win back this vital community asset, forging their partnership. She later intervened decisively to prevent the protagonist from abandoning the game after Nobu's disappearance, reigniting his resolve. As a travel companion, she voiced frequent complaints about outdoor sleeping conditions, showing visible relief when offered proper indoor accommodation with a bed by the ally Sasuke. Her strategic support included identifying specific powerful cards to counter opponents; notably, she located a burst card that revived and strengthened the protagonist's Souldragon spirit during a critical confrontation against Sengoku-Tiger.

Her personal card deck follows the purple color archetype, confirmed to include spirits such as Ginroukaku, Kinkokaku, Purple Smoke Dragon, and The DivineSpiritKing Amehoshi-no-Mikoto. Drawing inspiration from the historical Japanese strategist Kanbei Kuroda of the Kuroda clan, she uses the alias "Kanbei." She maintains an ongoing presence as both an instructor and information resource for the protagonist, providing critical analysis on opponents and game mechanics throughout their journey, including appearances during major events like a nationally organized tournament announced by the governing body.