Waruder is a robot samurai assassin contracted by SHADOW to kill Ichiro and a recurring character in Kikaider 01.
Unlike the other members of SHADOW, Waruder had a code of honor, seeking a fair duel with 01. He was also fond of human children and refused to hurt them. Of the course of the series he would develop feelings for Mari/Bijinder, only to be confused as to what he was feeling. He wrote several love letters to Mari, but Mari could not reciprocate as long as he tried to kill her friend 01.
He was initially hired by Big Shadow specifically to take out Ichiro. However, because of his fear of dogs, Waruder was unable to go out to face Kikaider. Thus, Big Shadow ordered Hakaider to kill any dogs near SHADOW's headquarters. Annoyed that Waruder was being given the task of destroying 01 instead of him, Hakaider challenged Waruder to a duel, but the robot samurai was able to defeat Hakaider.
Waruder then went to face 01. Along the way he encountered Mari, who was surprised by kindness he displayed despite being a member of SHADOW. Eventually, Waruder dueled 01 and was beaten back by him, but before 01 could finish him off Bijinder interfered in the battle and allowed Waruder to escape.
After SHADOW built a team of five "Warrior Ronin Robots" to defeat 01, Waruder chose to help 01 and Bijinder defeat the Warrior Ronin Robots, as he sought to defeat 01 himself. After Mari was injured defending 01 from them, Waruder tended to her injuries and discovered the miniature H-bomb SHADOW had implanted in her. Finding SHADOW's tactics distasteful, Waruder took out the H-bomb, and replaced it with one of his own power cores so Mari's body would remain stable. However, the removal of his own power core would lead to Waruder's lifespan being shortened to one week.
Because 01 had been marked with a special paint detectable by the Robots that could not be removed by most conventional means, Waruder assisted Mari in obtaining a special flower that could remove the paint. Because SHADOW had placed traps around the flowers, knowing that Mari would try to get them, Waruder went to grab the flowers himself so Mari would not be in danger. He also provided Mari with a pair of katanas passed down by his family that were capable of defeating the Warrior Ronin Robots.
However, after seeing Bijinder tend to an injured 01, Waruder became jealous of Mari's closeness with 01 and attacked him, violating his own code of honor by attacking an injured opponent. As Bijinder moved to defend 01, Waruder, confused by what he was feeling, stopped and allowed them to leave.
After the androids defeated the remaining Ronin Robots, Waruder challenged Kikaider 01 to a final duel to settle their rivalry. In the fated battle, Waruder would be decisively defeated by 01 kicking one his katanas into him. As Waruder shut down, he noted that he did not care about dying since he would have died in one week anyway without his power core, but lamented the fact that he died to 01 instead of Mari.