Taichi is the main character in V-Tamer. His Digimon is Zeromaru the V-Dramon, or Zero for short. When Taichi tried to enter a V-Tamer Tournament, he was rejected because Zeromaru wasn't supposed to exist - but he challenged the winner of the tournament, Neo Saiba to a match anyway. To Neo's shock and anger, he tied with Taichi, whom he called a "third-rate trash Tamer". Lord Holy Angemon later called Taichi into the Digital World, where he met a real Zero. Taichi and Zero eventually arrived at Holy Angel Castle, where Lord Holy Angemon told Taichi and Zero about the threat of Demon. Taichi later recieved a Digivice 01 from Whamon, another one of the guardians of the V-Tamer Digital World.
Rei is Neo's sister. In the real world, Hideto had called Rei, and because of that she was hit by a car and handicapped for life, and must go about in a wheelchair. However, she can walk in the Digital World. She met and is friends with Taichi, but Neo tried to kidnap her so she could be with him. She has a strange pendant that eventually turns out to be a Digimental that can evolve Digimon to a new form called Super Final.
Neo was called into the Digital World by Demon, who sought a Tamer to raise the Super Final egg he had prepared. Neo had several Digimon, and was the first Tamer to be seen jogressing Digimon together. Because when you jogress two Digimon together, the resulting Digimon's health is at full - he nearly beat Taichi and Zeromaru. But as Neo called Taichi a "third rate trash Tamer", Zero became furious and deleted Neo's Digimon. By this time, however, Neo had scanned much of Zero's data with his Digivices. Neo also let Taichi and Zero kill a Metal Greymon, which was devoted to him - but Neo didn't care for him at all, and was just using him to scan more of Zero's data. The Super Final egg finally hatched, and Neo turned on the Alias III, using Arkadimon Baby to kill Piemon, which made him evolve to Arkadimon Child. He then proceeded with an army to Holy Angel Castle, which barely defeated the assault. Later, Demon threatened Neo, but Arkadimon killed and absorbed him - but later it was seen that this was Demon's plan all along. Neo took command of all Demon's armies, and eventually Arkadimon evolved to Arkadimon Super Final through Rei's pendant. However, Demon was waiting for this very moment, and his data seized control of Arkadimon, transforming him into Demon Super Final, much to Neo's surprise.
Hideto was one of the Alias III that Neo called into the Digital World to aid him. He has an Omegamon (which later devolved into Metal Garurumon and War Greymon) for a partner - but they only reluctantly fought Taichi and Zero. Hideto was once Neo and Rei's friend, but once he called Rei over to see something on his V-Pet, and when Rei ran across the street she was hit by a truck and paralyzed from the waist down.
Mari was one of the Alias III that Neo called into the Digital World to aid him. She has a Rosemon for a partner, and very nearly stopped Taichi and Zero from saving Holy Angel Castle when Neo attacked it.
Sigmas was one of the Alias III that Neo called into the Digital World to aid him. He wears a mask and has a Piemon for a partner, but we know for certain that it was killed by Arkadimon.