Zense Reitetsu Ouji no Uma deshita: Hito ni Nattemo Anata wo Aishite Ii desu ka? Even after My Reincarnation, I Will Still Love My Prince

Synopsis

When I (a horse) awoke, I was in human form!? Lucania was the beloved horse of second prince Radius, alone in the world. However, when the prince was attacked, she lost her life. "Before the day of brightness, lead him from the depths of despair back towards the light..." By the power of the goddess, Lucania is reborn as a human. She goes to Radius, but he refuses the kindness of those around him, continuing to search for his vanished Lucania, believing she was still alive. Amidst the darkness of loneliness. "I will surely make you smile." Lucania hides her past as a horse and is determined to save Radius from his loneliness in the limited time she has. (Source: Kadokawa, translated)