Sagan commands New York Symphonica as Grand Maestro, leading humanity's strategic defense against D2 monsters from the organization's highest position. Though a celebrated hero for halting the D2 invasion—culminating in the Zagan Declaration ceasefire that established humanity’s temporary reprieve during the D2 dormancy—he wields authority subtly, maintaining a perpetually gentle demeanor. His traumatic exposure to soldier sacrifices during the initial D2 onslaught forged a complex worldview centered on martyrdom, crystallized in his philosophy: "Pain is true happiness." This conviction drove his extreme plan to lure all Earth’s D2s to his location for permanent containment, requiring North America’s annihilation as sacrifice. During this scheme, he directed his partner, the Musicart Heaven—who wields an umbrella-shaped device for offense and defense—to battle opponents. Sagan personally attempted to kill Takt Asahina, triggering Leonard Flyheart’s sacrificial intervention to shield Takt. His actions inflicted heavy casualties on opposing Symphonica members before Takt killed him, thwarting the mass sacrifice.