Shen (Hero) is the person whose body Kami borrowed to enter the 23rd World Martial Arts Tournament (without Goku's knowledge). Kami possessed the typically nerdy human, Shen, to disguise himself so that he could defeat Piccolo under the public's eye. He defeated Yajirobe in the preliminaries and defeated Yamcha in the finals (all under Kami's influence). Kami (still disguised as Shen) soon faced Piccolo and tried to seal him with the Mafûba, but Piccolo reversed it, and Kami was sealed instead. Luckily, Kami freed Shen (not wanting an innocent man like Shen to suffer for his failure) as he was being sucked into the Mafûba Container (small bottle). Shen was rendered unconscious, losing the match via 10 count (Knock Out) and woke up in the ring confused, having no memory of what happened while he was under Kami's control. He was praised by the crowd (who enjoyed watching him fight and was unaware of Kami's involvement) and, to his confusion, was commended for his martial arts prowess, even though he lost.
He was later seen being congratulated by his young, awe-struck son, who had been rooting for him during his fights in the tournament. Shen himself was dumbfounded by the whole ordeal at first, but rationalized it, thinking either that he must have been sleepwalking or drunk. He took it in stride and resumed his happy (hum drum) life.
Hero was presumably killed when Buu blew up Earth, only to be revived by the Dragon Balls and was presumably taken to Planet Plant in the Baby Saga until Earth was restored.
In Dragon Ball Z he briefly appears in Plans for Departure during Bulma's flashback when she recalls how Kami (inside Hero) and Piccolo spoke Namekian to each other at the Tournament.
His name is a pun on the first part of the Earth dragon's name, Shen Long, and it means "God" (the second part means "dragon"), which also make a play on Kami's name.In the English dub, the name "Hero" is used instead of Shen (likely to avoid confusion with the Crane Hermit Master Shen).