Hydra

Known as Haidora in the original Japanese, she is Valkyrie's younger sister, whom she pursued to Earth. She realized that if Valkyrie fled, she would be forced to take her sister's place at the wedding, a prospect she did not desire. However, she crash-landed on Akina's temple, where Akina sealed her powers, reducing her to a child's body similar to Valkyrie's. Unlike Valkyrie, though, her mind remains that of an adult rather than a child. Just as a kiss can restore Valkyrie, the seal on Hydra can be lifted at Akina's discretion. Hydra has a short temper and is quite tomboyish, acting rashly and prioritizing action over thought, which makes her prone to destroying anything that obstructs her. She can transform into a winged pink and yellow horse and possesses several other abilities. While living with Akina, she has taken up kendo and frequently teases Akina about her breast size and her feelings for Kazuto.
When the friendship between Hydra and Akina deteriorates, they can merge into a single entity known as Akidra.