Yodai Higashizawa acts as the Game Master for the first week of the Reapers' Game, wielding authority over player missions and challenges. He possesses a large, muscular frame, brown dreadlocks reaching his shoulders, and distinctive yellow eyes. His immense strength allows him to shatter concrete with his fists, though emotional volatility often compromises his effectiveness.

He consistently uses food-related analogies in his speech, especially when discussing players or game situations. During Week 1, he identifies Shiki Misaki's jealousy towards her friend Eri, a revelation shaping Shiki's character arc. His duties culminate on the seventh day with a direct confrontation against players Neku Sakuraba and Shiki Misaki. Following his defeat, the higher-ranking Reaper Megumi Kitaniji intervenes, declaring only Shiki may return to life and subsequently taking her hostage as Neku's entry fee for the next game.

In combat, he transforms into a Noise form called Ovis Cantus, a bipedal ram specializing in powerful close-range attacks. This form reflects his designated role as the "Combat" element within a Freudian Trio of Game Masters, emphasizing high durability over mobility. His defeat evokes a degree of pathos, suggesting layers beyond simple villainy.

Beyond his primary antagonistic function, he co-creates the in-universe game Tin Pin Slammer in the "Another Day" scenario, demonstrating involvement in Shibuya's subcultures without altering his core narrative role.