Tatsuyuki Misumi, known widely as "Smith" (Sumisu), is a 26-year-old professional shogi player ranked 6-dan. Standing 180 centimeters tall, he possesses a distinctive look featuring blond bobbed hair, glasses, and a beard. His professional reputation rests on a light and witty playing style, marked by particular skill in the "Windmill" shogi formation. He often fulfills a commentary or chorus-like narrative role within shogi sequences.

Misumi maintains a generally laid-back, occasionally aloof, demeanor yet cultivates meaningful bonds with fellow players. He shares a notably close friendship with Issa Matsumoto, whom he affectionately calls "Icchan," frequently shown spending time together. He exhibits a supportive dynamic towards Rei Kiriyama, doting on him as a junior while simultaneously respecting him as a fellow professional. This mentorship extends to leveraging Rei's connection to interact with Akari Kawamoto, for whom Misumi harbors subtle affection, often inquiring about her schedule or seeking ways to grow closer.

He expresses envy towards Kai Shimada's shogi study group, partly motivated by the meals provided, and occasionally invites himself to join. During one such session, his remarks—though lacking ill intent—alongside others in Shimada's group, provoked frustration, particularly in Shimada and Morio Shigeta.

Following a loss to Masamune Gotō, Misumi discovers and adopts a stray kitten named Ichigo (voiced by Asuka Nishi) found in a strawberry-marked box. Initially reluctant about pet ownership, he develops deep attachment to Ichigo, though the cat remains only partially warmed to him.

Misumi integrates smoothly within the shogi hall environment, maintaining professional camaraderie with peers like Matsumoto, reinforcing his role as a sociable yet understated figure within Rei Kiriyama's wider network.