OVA
Description
Kayin Amoh, originally from Scotland and later established as English, operates as a bounty hunter under the codename "Storm." His biological father was killed by bounty hunter Amou, who then adopted Kayin to atone for the murder. Amou was later killed by Sho Shinjo, the previous Battle Arena Toshinden champion, driving Kayin to seek revenge.

Kayin trained alongside Eiji Shinjo under Sho's guidance before Sho vanished. Learning Sho killed Amou strained Kayin's friendship with Eiji, though they remained rivals. While traveling, Kayin accidentally killed a scientist targeted by the Secret Society and, consumed by guilt, adopted the man's young daughter, Naru. He raised her while continuing his bounty hunting.

Kayin entered the first tournament to find Amou's killer. He subsequently left Naru for long periods during missions. When the Secret Society kidnapped Naru to coerce Kayin into the second tournament, he competed to rescue her. After her rescue, he formally embraced his role as her foster father.

A year later, fearing for Naru's safety due to his perilous life, Kayin placed her in an orphanage. He gave her his sword, Excalibur, before departing indefinitely. During the third tournament, Kayin discovered Amou had been an assassin for the Organization, the Secret Society's rival, and that Amou sacrificed himself to protect Kayin. This revelation allowed Kayin to fully accept being Naru's father, though he still chose to leave her for her protection.

Kayin's fighting style emphasizes kicks and electrical special moves: "Sonic Slash" (projectile), "Deadly Raise" (diagonal rising strike), "Shoulder Crush" (split kick), and "Scottish Moon" (somersault kick). His Desperation Move, "Hell's Inferno," unleashes a series of kicks and an elbow strike. He wields the sword Excalibur, linking him to Arthurian legend.

Kayin did not return for Naru. During the fourth tournament, Naru encountered a manifestation of Kayin as a ball of light, which returned Excalibur to her before vanishing, implying his death. Naru's search concluded without reunion. Kayin's story explores vengeance, redemption, and paternal guilt, culminating in his acceptance of Amou's sacrifice and his desire to shield Naru from his violent world.