TV-Series
Description
Princess Hydra, one of the eight Princesses of Valhalla, acts as a rival to Princess Valkyrie. She pursued Valkyrie to Earth, intending to forcibly return her to Valhalla and thereby escape being forced into Valkyrie's arranged marriage herself. This pursuit resulted in Hydra crash-landing on Akina Nanamura's shrine. Responding to Hydra's destructive actions, Akina sealed her powers, transforming her physical body into that of a child. Unlike Valkyrie, whose mentality regresses in her child form, Hydra retains her adult mind and personality despite her appearance. Akina alone controls the seal's release, though the duration of Hydra's subsequent adult transformations is inconsistent and unclear.

Hydra possesses a headstrong, short-tempered, and tomboyish personality, contrasting Valkyrie's gentleness. She frequently acts rashly, prioritizing action over thought, often leading to property damage or comedic physical retaliation from Akina. A recurring point of contention involves Hydra teasing Akina about her breast size, yet this coexists with a developing mutual respect and friendship. Hydra takes pride in her feminine appearance, expressing marked distress over the initial shrinkage of her breasts due to Akina's sealing magic. Her relationships with other Valhallan princesses are complex: she shares a competitive but ultimately amicable bond with Valkyrie despite their clashes, finds Princess Laine irritating, and is frequently annoyed by Princess Chorus.

Residing with Akina, Hydra adapts to Earth life. She takes up kendo, developing considerable swordsmanship skills that reflect her earlier Valhallan combat training. This period fosters an unexpected partnership with Akina. When their arguments escalate significantly, their mutual antagonism triggers a fusion dance, merging them into the powerful entity Akidra, wielding their combined abilities. This fusion state persists only while they remain in conflict, dissolving if they reach agreement or harmony. Hydra's distinct adult-form abilities include flight, superhuman strength, energy projection, and transformation into a winged pink and yellow horse. Her transformation sequences sometimes involve clothing inconsistencies, causing moments of embarrassment.

Her relationships with Earthlings evolve. She forms a strictly platonic friendship with Kazuto Tokino and maintains a generally neutral, occasionally contentious, friendship with his sister, Rika. Her closest Earth bond is with Akina, evolving from forced coexistence and mutual frustration into a deep, albeit combative, partnership defined by their unique fusion capability.