Jiro does not really understand why and how he was brought into this world and why the DARK is attacking them. Jiro is not willing to transform into Kikaider. Jiro/Kikaider, however, is a robot imprinted with a "conscience circuit," so that he can act more like a human. As a result of this circuitry, Kikaider suffers from the agony of being neither truly human nor truly robot. As he spends time with Mitsuko, he gradually becomes conscious of what it really means to be "human"...
Kikaider is supposed to protect humans. However, the evil Professor Gill who funded the scientist sends Kikaider's brother figures, robot army corps as hatchet men in order to destroy Kikaider who is in the professor's way. This means to Kikaider having to kill his own brothers in order to protect humans. The DARK with no mercy keep sending the assassin robots to Jiro and he is forced to transformed into Kikaider and fight against his "brother robots"!
NOTE: This Manga reads right to left.