Fen Barefoot made his first and only appearance in Battle Arena Toshinden 4, as an initially playable character.
Fen is a brash young boy with a pet pig named Wolfy, which follows him around wherever he goes. While Fen usually appears as having a cheerful personality, he has a troubled past. He lost both his parents when he was young and from then on lived with his grandfather, where the two made a living by fishing.
One day, he found a strange man (Mondo), wounded and carrying a spear, in the forest behind their house. He and his grandfather tended to his wounds and helped him recover and in return, the man taught Fen some of his fighting techniques.
One year later, after the warrior had left, another strange-clothed man came to the house. He asked Fen's grandfather if he knew the whereabouts of the man they had helped. When his grandfather had said no, the man, known as Genma, killed him. Vowing to do whatever it took to gain vengeance, Fen formed a team with a girl named Puella Marionette and her friend Lancelot Lakeknight, to compete in the fourth Toshindaibukai.
- His name is a reference to Barefoot Gen.