“Sanda” unfolds in a dystopian Japan where drastic governmental steps are taken to combat declining birth rates. The story follows 14-year-old Kazushige Sanda, voiced by Ayumu Murase, who inherits the magical ability to transform into his legendary ancestor, Santa Claus, portrayed by Hiroki Tochi. After braving the freezing cold to assist a child on a wintry Christmas, the only step left to activate his powers is donning something red. When he balks, his classmate Shiori Fuyumura, voiced by Umeka Shoji, eager to invoke Santa, stabs him so that his blood dyes his shirt red. From there, the narrative takes even more bizarre turns.

Adapted from Paru Itagaki’s manga, the same creator behind “Beastars,” “Sanda” is brought to life by the animation studio Science SARU, known for “Dandadan.” Available for streaming on Prime Video globally, the series is reaching its conclusion, with the final episode set for December 18. If it successfully wraps up its storyline, “Sanda” is poised to be remembered as a unique addition to alternative holiday classics.

In Itagaki’s imaginative portrayal, Santa Claus is akin to a superhero. This version of the jolly figure is robust and muscular, impervious to fire from all the chimney descents. Traditional elements of Santa lore receive inventive spins: his ability to discern good and bad behavior is depicted through a built-in lie detector that causes objects to drop when lies are told. His feet house sleigh-blades similar to Wolverine’s claws, and he possesses a rapid healing factor that allows him to survive even headshots.

Paru Itagaki’s vision of Santa Claus is basically a superhero. He’s the most muscular old man you’ve ever seen and going down chimneys all the time means Santa is fireproof. Other traditional Santa lore gets interpreted in creative ways: “He knows if you’ve been bad or good” translates to him having a built-in lie detector (objects fall to the ground when people lie to him) and sleigh-blades pop out of his feet like Wolverine’s claws. He’s also got a Wolverine-level healing factor, making him capable of surviving gunshots to the head.

While Santa’s powers resemble Wolverine’s, the superhero whose Sanda’s circumstances most closely parallel is Shazam/Captain Marvel. Rather than saying magic words to transform into an adult hero, Sanda becomes Santa by wearing red and changes back to Sanda by eating “Bratty Bean” jelly beans. What makes this transformation extra complicated is that it’s not only physical but psychological. Santa must protect all children and can’t fall in love with them, while Santa’s adult mindset starts to override the still-young Sanda. It makes for a strange coming-of-age metaphor of the type which anime excels at; if you’re a fan of “FLCL,” “Sanda” delivers similar vibes in addressing the confusion of adolescence via action-packed insanity.

As if being simultaneously a middle schooler and Santa wasn’t hard enough on its own, the world of “Sanda” has made it extremely difficult for anyone to grow up. Because there are so few kids, society tries to keep them kids for as long as they can. Children are born into pre-arranged marriages and sexual education is verboten in Daifuku Welfare Academy’s “trauma-free curriculum.” Medical advances have eliminated the need for sleep and kids are banned from sleeping to slow down physical maturity. Fuyumura has broken this rule, experiencing growth spurts, and deals with broader questioning of her identity and sexuality.

The sheltered status of children goes so far in this future that it’s not a crime for kids to kill adults; young murderers take special classes in the school’s basement. Adults in this world are obsessed with their own appearance of youth through extreme plastic surgery. Headmaster Hofumi Oshibu (Toshihiko Seki) is 92 years old and goes to extreme lengths to seem younger, replacing almost all of his organs with cybernetics. Only the wrinkled skin on his hands indicates his true age.

As you would expect from the creator of “Beastars,” “Sanda” goes to some dark and uncomfortable places. It contains bloody violence and complicated sexual themes, so it might not fit into every viewer’s Christmas stocking. However, for anime fans seeking holiday viewing that challenges as well as entertains, it’s a streaming gift well worth unwrapping.