Kayin is a friend of Eiji
Shinjo and is a bounty hunter, going by the name
of Storm. He was trained in sword-fighting along with Eiji by Eiji's older
until he suddenly disappeared. Kayin then entered the first Toshinden tournament
to avenge his father's recent death, who he learned had been killed by
a participant who won the previous tournament. He eventually learned that
Sho was the perpetrator and his friendship with Eiji was nearly shattered
because of this.
Kayin was then forced to enter
the second tournament after his adoptive daughter, Naru, was kidnapped
by the Secret Society. At the end of the event, he managed to help bring
down the fall of the Secret Society and rescue Naru. However, he then discovered
that they were being targeted by the Organization. He participated in the
third tournament hosted by it and managed to help destroy the Organization.
However, he realized that Naru would always be in danger because of him
and he decided to leave her in a housing institute. He handed down his
Excalibur sword to her and then disappeared.