Harmony Unleashed: Equestria Campus Supremacy - The Movie: Secret Origins of a Day Princess

Harmony Unleashed: Equestria Campus Supremacy - The Movie: Secret Origins of a Day Princess is an animated science fantasy film based on the television series of the same name. It is part of the Humanoidverse film projects and the second film adaptation from the television series, as well as a prequel to the television series set 20 years before the events of ECS. The film is directed by Asaph Fipke and Akira Amemiya and written by Christy Marx, Jordan Roberts and Nathan Long with a story by Aaron Montalvo.

The film is released in theatres and home video simultaneously in November 23, 2016 from Twentieth Century Fox Home Entertainment and Metro-Goldwyn-Mayer.

Premise
The origin story about the life of a younger Celestia and Luna, as they live their lives facing High School in Dream Valley Academy, Celestia's crush on Prince Sombra, and other stuff growing up that might lead her to face her own sister and her life before she became principal of Canterlot High School.

Cast

 * Emilie-Claire Barlow/Kikuko Inoue as Celestia
 * Nicole Oliver/Inoue as Celestia (older, as Principal Celestia)
 * Tabitha St. Germain/Ami Koshimizu as Luna
 * St. Germain/Koshimizu & Aki Toyosaki also voices an older Luna and Rarity.
 * Nolan Gerard Funk/Takuya Sato as Prince Sombra
 * Big Jim Miller/Takuya Kimura as King Sombra (cameo)
 * Samantha Newark/Nana Mizuki as Twilight
 * Diana Kaarina/Kokoro Kikuchi as Young Twilight Velvet
 * Tara Strong/Aya Hirano as Twilight Sparkle
 * Patrick Stewart/Tessho Genda as Starswirl the Bearded

Trivia

 * Emilie Barlow's role of Celestia was due to a mistake by a Wikipedia/Wikia contributor mistaking Nicole Oliver's role of Cheerilee to Barlow in 2011, who never was involved in the series.