Seri Tatekami, a second-generation Fafner pilot, is intrinsically linked to her island’s core and its defense networks. Introduced as a biology-focused student, she leads club activities centered on studying local insects through ethical, non-invasive traps. Her capacity for profound bonds defines her, particularly her friendship with Tsubaki Minashiro, the island’s enigmatic core. Their connection sparks during a crisis when Seri reaches out to the isolated Tsubaki, forging loyalty that persists through Tsubaki’s integration into the island’s protective systems.

As conflicts with the Festum escalate, Seri evolves from civilian to combatant, piloting the Fafner Mark Zwolf with tactical skill. She wields armaments like the Levin Sword and Shotgun Horn during pivotal missions, including the Sixth Operation Azure, where she aids in safeguarding critical assets such as the L-Boat. Battles expose her to the Festum’s anguish—their agonized cries drive her to craft grave markers for fallen foes, blending battlefield pragmatism with empathy.

Her devotion to Tsubaki anchors her dual path. Balancing medical studies with hands-on care for the island’s core, she heeds advice to pursue both general and specialized training, ensuring Tsubaki’s stability. During crises, Seri temporarily merges with the island’s systems as a substitute core, sharing Tsubaki’s burden and cementing her role in the infrastructure’s survival.

Post-conflict, she engages in community traditions like the Tanabata Festival and rekindles ties with peers such as Rina Nishio. Her reconciliation efforts extend to mentoring newcomers like Sakura Kondou and honoring fallen comrades at memorial sites, bridging the island’s history with its future. Physical shifts, like her hair whitening over years, mirror her prolonged exposure to the island’s environment. Her journey weaves resilience, adaptability, and the interplay of vulnerability and strategic resolve, framing her as a linchpin in humanity’s struggle to coexist and endure.