Sasaki holds a seat on Sidonia's governing council, wielding authority within the ship's hierarchy. This role entails shaping critical decisions on Sidonia's operations, defense against the Gauna, and population-wide policies. The character appears in vital strategic meetings with Captain Kobayashi and fellow councilors, especially during emergencies threatening Sidonia's survival. Following the integration of the Gauna-human hybrid Tsumugi Shiraui into Sidonian society and defense, Sasaki contributes to council deliberations assessing her status, capabilities, and implications aboard the ship. The character is also present during events leading to the confrontation with the rogue scientist Ochiai, participating in decisions surrounding his capture and containment after his actions jeopardize Sidonia's security. A ten-year peace ensues after Sidonia reaches Planet Nine. Throughout this period, Sasaki remains active in governance as society transitions toward planetary colonization. The council, including Sasaki, oversees military readiness drills and maintains defenses despite the apparent absence of Gauna attacks. Sasaki is involved in the strategic response when the Gauna return in overwhelming force, culminating in the massive assault of the final battle; council decisions during this conflict directly impact Sidonia's survival tactics and resource allocation. The character's presence is documented during critical moments involving the immortal leadership cadre, including discussions about Nagate Tanikaze's origins and connection to Sidonia's history. After the Gauna threat is defeated and humanity successfully colonizes Planet Nine, Sasaki remains among the council members governing those who choose to stay aboard Sidonia rather than settle on the planet. This council, with Sasaki, subsequently embarks with Sidonia on a continued journey into deep space.