Natsu awoke with three others, a disorienting blankness where memory should have been. They found themselves on an unfamiliar island, and together they began the daunting task of understanding their situation and finding a way to endure.

Certain that Botan had taken them, Natsu and Arashi slipped away from the encampment, venturing into the shadows. There, they encountered another survivor. It was then that Botan finally revealed the information she possessed.

Natsu’s propensity for mishaps inadvertently guides Team Summer B toward the rest of their companions. Her recollections prove invaluable, helping them ascertain their whereabouts and chart a course for what follows.

Through the remnants of old Kobe, Arashi, Natsu, and Semimaru discover the Team Autumn encampment. It appears they flourish, yet a cruel authority governs their ranks.

Amidst the shattered remnants of Tokyo, Natsu, Arashi, and Semimaru encounter the lone survivor of Team Winter. Meanwhile, Team Spring reaches the summit of Mt. Ogino Fuji, where they discover Natsu’s message.

Despite Fujiko’s reservations, Aramaki has joined Team Spring. Hearing that Aramaki has encountered someone matching the description she seeks, Hana resolves to find Arashi.

Hana and her companions stumbled upon a vast, subterranean shelter. Within its depths, they discovered a survivor's diary, detailing the grim destiny that awaited those who had sought refuge there.

The Spring settlement lay in ruins, deserted and desolate, a grim testament to Hana’s group and the Team Autumn survivors. Momotaro awoke amidst unfamiliar faces.

For survival, Hana and the others rely on the cooperation of Team Summer A. Aboard the vessel, Hotaru’s cousin, Hibari, tells Natsu that Hotaru is fading.

Ango often remembered the unforgiving discipline of the program's early years, and the brutal final test that had narrowed the ranks to those few who would become the core of Team Summer A.

A chilling certainty settled upon Hana: to remain in the village was to invite death at the hands of Ango. Meanwhile, Natsu and the others reached the shore, finding themselves near the ruins of the old Autumn settlement.

Ryo directed Hana to accompany him in their search for an underground water source, placing her in a precarious situation. Deep within the caves, Ango remembered Shigeru.

With the departure of Team Summer, Ango and Ryo are left behind, while Haru and the others grapple with the loss of Hana. Aramaki departs the settlement, clinging to the hope that Hana somehow survives.

Anticipating an ambush, Ango and Ryo located and observed Team Summer B, only to find themselves unexpectedly greeted with warmth by the laid-back group.

The arrival of the two new members offered a welcome boost to Team Summer B. As familiarity grew, however, Ryo found himself questioning their chances of enduring. Meanwhile, Ango began to perceive in Natsu a reflection of Shigeru.

The group reveled in the ease of life aboard the ship, yet Ryo put their resilience to the test. Natsu’s casual remark about Team Summer B being comprised of failures ignited a sharp displeasure in Ango.

A sense of unease prompted Botan to examine the possessions of Ryo and Ango, while the remaining group members continued their search for Arashi. Meanwhile, a lone survivor gained a deeper understanding of the surrounding wilderness.

Team Summer B found itself ensnared in a thick growth of algae. Seeking a way out, they discovered a large vessel and began to explore it, though Botan remained cautious. Stranded, Arashi spotted a kite attached to the ship.

A sudden lurch threw the team members apart. Arashi moved quickly to offer assistance, while Botan’s group began to make a discovery of their own.

Ango’s visions plunged him and Arashi into dangerous circumstances. Meanwhile, Semimaru narrowly escaped death, and Natsu steeling herself, gathered the resolve she needed.

The wilderness, often perceived as refuge, can prove a snare for creatures great and small. Simultaneously, a bacterium with a voracious appetite for iron is gaining a foothold within the vessel.

Fujiko and Chisa found Hana waiting for them. Onboard the vessel, the launch preparations for the missiles commenced, while Team Summer B received information regarding Ango’s history and the nature of the test.

Hana tentatively re-enters the world of human interaction. The members of Team Summer B collaborate, working with their hands to neutralize the missiles, though a string of access codes presents unforeseen difficulties.

The vessel is beset by escalating bacterial infection. Amidst this growing threat, the missile countdown proceeds, and the crew races for the escape pods.