1. Spring Begins

Along with three others, Natsu wakes up with no idea what's happened. The four of them reach an island and try to figure out a way to survive.

3. Light Snow

Natsu's clumsiness indirectly leads Team Summer B to the rest of their group. Her memories help them figure out their location, and their next moves.

4. Autumn Begins

Arashi, Natsu and Semimaru stumble upon the Team Autumn settlement in the former Kobe region. They seem to be thriving, but their leaders are tyrants.

5. Heavy Snow

In the ruins of Tokyo, Natsu, Arashi and Semimaru meet the sole survivor of Team Winter. Team Spring reaches Mt. Ogino Fuji and finds Natsu's message.

6. Grain Rain

Aramaki joins Team Spring, despite Fujiko's doubts. Hana decides to search for Arashi after hearing that Aramaki met someone who fits his description.

7. Winter Solstice

Hana and her companions discover a massive underground shelter. They find a survivor’s diary and learn the cruel fate of those who took refuge there.

8. Summer Solstice

Hana's group and the Team Autumn survivors find the Spring settlement destroyed and abandoned. Momotaro wakes up among strangers.

9. Lesser Heat

To survive, Hana and the others work together with Team Summer A. On the ship, Hotaru's cousin Hibari tells Natsu that Hotaru is slowly dying.

10. Cold Dew

Ango recalls his harsh upbringing in the program and the brutal graduation test that winnowed the survivors down to the final Team Summer A members.

11. Greater Heat

Hana becomes convinced that Ango will kill her if she stays in the village. Natsu and the others make landfall near the former Autumn settlement.

12. End of Heat

Ryo orders Hana to join him in searching for a water source underground, putting her in a vulnerable position. In the caves, Ango recalls Shigeru.

13. Frost Descends

Team Summer A banishes Ango and Ryo as Haru and the others mourn the missing Hana. Aramaki leaves the settlement believing she is still alive.

14. Summer Begins

Expecting a trap, Ango and Ryo find and observe Team Summer B, but they are unexpectedly welcomed by the easygoing group.

15. Grain in Ear

The two newcomers help Team Summer B. As they get to know the group, Ryo doubts their ability to survive. Ango begins to see Natsu as Shigeru.

16. Autumnal Equinox

The carefree group enjoys life at sea, but Ryo tests their survival skills. Natsu reveals that Team Summer B is for dropouts, angering Ango.

17. Vernal Equinox

Suspicious, Botan searches Ryo and Ango's belongings while the others look for Arashi. Elsewhere, another survivor learns about the wilderness.

18. White Dew

Team Summer B gets stuck in a bed of dense algae. they find a large ship and investigate, but Botan is wary. Stranded, Arashi sees the ship's kite.

19. Winter Begins

The team members are separated after the ship's sudden movement. Arashi makes his way to help as Botan's group makes a discovery.

20. Lesser Cold

Ango's hallucinations lead to perilous situations for him and Arashi. Semimaru has a brush with death while Natsu gathers her courage.

21. Grain Full

A sanctuary in nature becomes a trap for small mammals and humans alike. Meanwhile, an iron-eating bacteria begins to spread throughout the ship.

22. Rain Water

Fujiko and Chisa reunite with Hana. On the ship, the missiles begin launch prep while Team Summer B learns about Ango's past and the test.

23. Greater Cold

Hana readjusts to other humans. Team Summer B works together to manually disable the missiles, but a series of passcodes complicates the process.

24. Pure Brightness

Problems persist in the ship as the spreading bacteria begins attacking. The missile countdown continues as the team makes a mad dash to exit.