Eishiro Sugata serves as president of the New World Discovery Club at Sorami High School, dedicating himself to researching the enigmatic "New World"—a black hole-like anomaly hovering over the city—as well as Angeloids and the realm of Synapse. Possessing high intelligence and combat abilities, he lives unconventionally in a riverside tent and wears only his school uniform, lacking other clothes. His demeanor remains consistently calm and collected, often weaving references to historical explorers like Magellan and Columbus into his narrations. Born into a prominent political family, Sugata admired his older brother, bonding over a shared passion for flight and gliders. An argument preceding a test flight led Sugata to neglect inspecting the glider properly, resulting in his brother's fatal accident when a wing detached mid-flight. Blamed for the tragedy, Sugata was disowned. His younger brother, Yuugo Sayama, became the family heir. This event fueled Sugata's drive to discover the "New World" as atonement, motivating him to establish the New World Discovery Club. Family ties later resurface when Yuugo recognizes Hamuel's resemblance to a deceased childhood friend, confirming their sibling relationship. Sugata witnesses the Angeloid Ikaros crash-land near Tomoki Sakurai, instantly recognizing her connection to the New World. He provides shelter and snacks for the Angeloid Astraea, deducing her mission, and harbors animosity toward the Angeloid Chaos. During Hiyori Kazane's arc, he identifies her as an Angeloid, though his memory of this is later erased. In the final conflict, he infiltrates Synapse to reprogram the Rule Obelisk, sacrificing himself during the process. Tomoki Sakurai's subsequent wish resets reality, restoring Sugata to life. His involvement extends to spin-off media. He plays an important role during the second half of "Daisuki desu! Mahou Tenshi Kosumasu." In "Yūryō Bukken Mō Dame Sō: Furo, Toilet to Tenshi wa Kyōdō Desu," he appears briefly in a flashback and later contacts Yuugo Sayama by phone. During this call, he reveals his knowledge of Synapse's secrets and Hamuel's true identity, demonstrating his ongoing commitment to unraveling the New World's mysteries and its heavenly connections.