My Little Pony: Thousand Years of Friendship Redemption

The protagonist Tian Chou has an unusual past - she was originally Princess Qian Mo, one of the five princesses a thousand years ago. She once lived a happy life with her four friends, Princess Yuanyang Haiyin, Princess Cuimei Maowan, Princess Yanyang Zhuochen, and Princess Hope Zhaoqi. They went on adventures together, and their friendship was profound. Tian Chou also found his mission in this friendship. However, the invasion of the Soul-eating Demon King broke the peace, and the creatures along the coast were devoured. The five princesses struggled to resist but were unable to defeat them. When Zhao Qi led everyone to seal the Demon King with the magic power of life, the Demon King desperately devoured the four princesses except Tian Chou. Tian Chou survived under the protection of Zhao Qi, but lost his best friend forever. Over the long years, Tian Chou tried to make new friends, but due to the life span gap, he experienced separation again and again, and finally walked into the southern desert to sleep in despair. When she woke up after a thousand years, she lost her horns and wings, forgot her life experience, and became an ordinary earth pony. Returning to Tianchou in Equestria, he marveled at the changes over the millennium and just wanted to live an ordinary life. Destiny allowed her to meet Twilight Sparkle and six other ponies, and together they fought against Nightmare Moon and became friends. In adventure after adventure, she gradually regained her understanding of her mission... [Alias: Path to Redemption, Obsession and Protection]