Season 1 (2025)

1. Everything's Bright, Am I Aging?

On a Dec 25 without Christmas, Sanda is attacked by classmate Shiori. Mistaking it for love, he awaits her confession, but hears something else.

2. Candies, Canes, Kisses, and Blades

Amaya learns Sanda is Santa, restrains him and Shiori to force a kiss. Santa refuses, unlocks sled power to escape. Then Headmaster Oshibu appears!

3. Charred Fruit Tastes All the Sweeter

Sanda gains lie-detecting power. Shiori tries to use it to find Ono, but doubt overwhelms Sanda. Shiori then tells a self-harming lie.

4. Zeus, Smasher of Textbooks

At a funeral, Santa fights Yagiuda but fears his power. His resolve returns, shattering the roof and leaving him exposed before all.

5. A Typhoon in a Snow Globe

Sanda vows never to love, but in a typhoon his message to fiancee Niko fails and he's drawn to her. The next day, Yagiuda arrives as a teacher.

6. Cyborg vs. Santa Claus

Santa blocks Headmaster Oshibu from attacking adult Ono, but the enhanced 92-year-old overpowers him. Santa asks the kids for their belief to fight.

7. Double-Faced Carnivorous Plant

Amaya ends his friendship with Sanda to save him. Meanwhile, the scarred Oshibu, comforted by Yagiuda, turns to Class 10 students who killed adults.

8. Love, the Most Selfish Thing There Is

Saved from Namatame by Shiori, Santa vows to harden his heart, but when Niko asks for a kiss, Sanda panics and almost transforms before her.

9. A Fake Flower, Yet Its Roots Rot

Tetsudome says Santa lacks grit. With her aid Sanda becomes dark Santa, but doubts himself. After meeting Namatame again, he vows not to fight kids.

10. You, an Everlasting Moment

At the Peak of Youth Ceremony, Niko steals Sanda's first kiss at twilight. Meanwhile Yagiuda faces Namatame alone, offering himself as decoy.

11. Flashback Attack

Namatame wrecks the ceremony. Eating yakisoba, she's met by Sanda in child form. His body starts breaking down as Ono's own changes grow.

12. Episode 12