Miyuki's Avalanche (高良ミユキの雪崩 Takara Miyuki no Nadare ) is a 1986 anime short film directed by Hiroshi Takajima and distributed by Toho in Japan and Walt Disney Pictures in North America. This short film was shown at various universities across Japan from January 12 to January 26, 1986. The film was released in theaters to coincide anime films on March 7, 1986. Set before the events of Star Trigon, the film follows the story of Miyuki Takara who must retrieve spring after she caused an avalanche on accident while hiking on Mount Tsukuba. The film was instantly a success and was even nominated for an Academy Award.
The film begins with Miyuki Takara climbing up Mount Tsukuba to find a hidden gemstone inside a volcano. The gemstone allows anyone to be completely invulnerable to ice, and touching it first allows the owner to possess cryokinetic powers to create and manipulate ice. Shortly after she touches the gemstone, the volcano erupts and sends a massive avalanche to its surrounding cities, covering them in snow and perilously dropping their temperatures.
With Miyuki worried about what she had done, she realizes the gemstone does not make her cold at all and makes her warm instead. When Miyuki tries climbing down Mt. Tsukuba, the ice she is walking on freezes and she slips and falls and sends her sliding down the frozen path. When Wataru finds Miyuki at the end of the path, he finds her seriously hurt and takes her to a nearby hospital. At the hospital, Wataru realizes that her glasses have been cracked and uses a Mending Charm to repair it.
Wataru asks Miyuki to explain what had happened with her experience, and she tells Wataru that she was trying to climb Mt. Tsukuba to find a gemstone that can make her warm permanently. When a doctor asks Miyuki if she needs something to eat, Miyuki declines and with a swish of her hand, she freezes the doctor's face on accident. Wataru tells Miyuki that she had no knowledge that the gemstone gave her cryokinetic powers to create and manipulate ice. Miyuki begins to cry over what she had done after getting the gemstone, and the trouble she had done.
When Wataru goes back to the hospital the next day, a doctor tells Wataru that Miyuki had received a letter from the Driller Institute. When Wataru arrives at Miyuki's room, she gives her the letter and upon opening it, she had received a warning from Masuyo Toby that she had violated the Spell Card Abuse Act of 1892, stating that she had performed a Freezing Spell on a muggle.
Once Miyuki is discharged from the hospital, she goes back to the core of Mt. Tsukuba to find more about what the gemstone can do. Upon arriving where she found the stone, she hears a mysterious voice from the gem, questioning Miyuki about the effects of the stone. Miyuki replies to her that somebody once told her about it, and about what happened upon finding it.
The stone then tells Miyuki that she is now a yuki-onna, and can take anyone's warmth away. Miyuki realized she could do this to Dr. Manhole and asks the stone how she can restore spring. She also realizes that prom is approaching, and she doesn’t want it ruined. On the day of the event, Miyuki reappears at Mt. Tsukuba in her blue prom dress robes. Despite holding the yuki-onna effect, it tells her to get six sapphires from a maze in the volcano.
Upon getting the sapphires, it performs the ritual to make Miyuki a true yuki-onna, with her getting snowed on and after the effects, she later reappears with her hair curled and inside a beautiful white Victorian-style gown made entirely of snow, alongside the sapphires she was told to get on it. Once prom begins, and when Wataru sees Miyuki, he tells Miyuki he wants spring to come back. Miyuki tells him that the only way for spring to come is if he gives her "some love". Miyuki then asks Wataru to say "I love you" at least 100 times in order for the spell to work.