Caleb Walker

Caleb Walker (Hakaider) is the "younger brother" of Paul.

After Paul managed to defeat Black Crow in battle, the evil Professor Gill revealed of DARK's intention to create a powerful soldier known as Hakaider, whom Gill stated was more powerful than Paul himself.

Later on when DARK managed to kidnap Dr. Komyoji (who regained his memories), they forced him to make Caleb under the influence of drugs by DARK to "correct" his mistake of creating Kikaida. Unlike other DARK androids, Caleb is technically a cyborg as Gill had Dr. Komyoji's brain transplanted into the very android he created, to use as a shield against Paul. He soon revealed himself in battle form to Paul once he broke out of prison, challenging his older brother to a duel.

Although Paul was able to hold his own against his younger brother (despite having a malfunction at the time), he was ultimately defeated once Hakaider used the White Crow's missiles. Hakaider then almost succeeded in killing Kikaida, but was forced to stop fighting due to his time limit. Later on, Gill revealed that Caleb needs periodic blood transfusions from Dr. Komyoji's body each hour, otherwise it would kill both of them.

Afterwards, the cyborg revealed himself to Mitsuko, Masaru and Hanpei, where he lied and stated that he was programmed by Dr. Komyoji to awaken from his deep slumber in case Paul ever malfunctioned. He soon somewhat gained their trust once he saved them from Purple Starfish's attack. Once questioned by the Destructoid over his motives, Caleb stated that he hates unfair plans and ordered him to tell Gill not to interfere.

This caused the Destructoid to greatly hate the cyborg, to the point of escaping from Paul once Caleb appeared in front of them from afar. After Paul learned of Dr. Komyoji's state and defeated Purple Starfish in battle, the cyborg challenged his brother for a rematch. Despite Paul's unwillingness to fight him, Hakaider left him no other choice by pointing his Hakaider Shot towards him. He then told Paul that he prefers to not use weapons against an unarmed opponent before attacking him with powerful moves. Trying to end the battle as quick as possible, Paul used a weakened version of his Ginga Hurricane against Caleb, defeating him without inflicting fatal injury. This allowed Paul to escape from their duel, with Hakaider grudgingly stating he is the only one capable of killing Paul.

When Masaru wrongly confronted Paul over killing his father, Caleb appeared in the midst of his confusion, with Masaru siding over him. Asked who he is by Paul, Caleb revealed his name and told Paul he is his brother. Paul did not believe Caleb's words, not knowing it to be the truth.

Acting very cocky, Caleb then referred Paul as junk and tauntingly challenged him to a duel. Despite his willingness to fight, Paul decided to run when Mitsuko pleaded him not to. The next day, Caleb gave the Death Whistle to Masaru after showing it's effects to him, with Caleb telling him to use it on Paul, with Masaru agreeing without a second thought.

Once Paul raced on his Side Machine with a small child helping him find the kidnapped children, Hakaider attacked them with his White Crow, which Paul and the child narrowly escaped from.

Arriving later on when Masaru used the Death Whistle on Grey Grasshopper, Caleb grew slightly annoyed once he found out Paul wasn't there. Despite slightly being annoyed, Caleb told them to escape while he confronted the Destructoid. Asked who he is, Caleb revealed his battle form and told Grey Grasshopper not to lay a hand on them. Questioned whether he was a warrior of DARK for his actions, Caleb harshly replied to Grey Grasshopper that he was not a feeble minded robot like them, and told Grey Grasshopper if he is still bent on going after them, he would have to face his wrath. Despite Grey Grasshopper threatening to tell Gill about this before leaving, Hakaider only sneered and stated he was not afraid.

When Masaru did later find Paul who was winning in his fight with Grey Grasshopper, he used the Death Whistle on him and called for Caleb. Seeing that Masaru was aiming the Death Whistle at Grey Grasshopper instead, Caleb told him to properly aim for his prey, with Masaru surprised at the predicament. Immediately afterwards, Hakaider broke through Gill's room, which Gill questioned him for. Stating that he heard Gill was looking for him, he was confronted by Gill for interrupting Grey Grasshopper, which Hakaider aloofly confirmed and flew out the ceiling, making Gill curse him.

Once Paul saved Mitsuko and Masaru from Grey Grasshopper, he told Masaru that he would rather die than continue to be distrusted by him. This was followed with Caleb's appearance, where he easily subdued Grey Grasshopper and challenged Paul to a fight. Deciding to wait for Paul to defeat Grey Grasshopper, he saw their fight through. Suddenly though, Gill's flute combined with Grey Grasshopper's speaker allowed them to fully control Kikaider, forcing him to fight Caleb. Revealing his identity as Hakaider to Kikaider, Caleb fought him in battle. Their battle soon ended once Mistuko and Masaru interrupted Grey Grasshopper, allowing Paul to regain his sanity. Despite Mistuko and Masaru being chased by Grey Grasshopper, Hakaider would not allow Paul end their fight to save them. In a struck of luck however, Hakaider's time for blood infusion came, forcing him to end their battle.

Personality
Caleb is more of an antihero as he saved Mitsuko, Masaru and Hanpei from DARK`s Destructoids a number of times and tried to fight fairly against Paul (the only exception being their last fight) showing somewhat good sportsmanship (although he did try to trick Paul's friends to use against him) and a sense of honor.

However he could be quite ruthless and mean towards his enemies as he mocked Paul and DARK`s members several times, saying that they are inferior compared to him (somewhat hinting a sense of insecurity) which shows his narcissistic side. He could also be clueless as he didn`t realize Dr. Komyoji`s brain was in his body (until Masaru told him later on) and didn`t understand Paul`s reasons for not wanting to fight him. While he often boasted his supposed superiority to other members of DARK, he was in fact following orders like other members.

Since Professor Gill told Hakaider the only reason he was born was to destroy Kikaida, Hakaider only wound up listening to that order while ignoring every other order.

Throughout the series he showed an obsession with defeating Paul to the point where he would even risk Mitsuko, Masaru and a small child`s lives just to have a chance of defeating him.

Despite these negative sides to his personality though, he does seem to care about his allies (aside from grunts) as he showed remorse for killing Red Mine Toad and later went insane partly because of that. Unlike most of his older brothers who has a Conscience Circuit (Aside from Orange Snail who was possibly good) Caleb wasn`t created by Dr. Komyoji consciously, which was the primary reason for not having a Conscience Circuit installed.