It was based on the manga chapter of Inazuman called The Boy with the Guitar (ギターを持った少年, Gitā o motta shōnen).
The two grow closer together but the relationship development halts when a mysterious flute playing causes Jiro to attack Mitsuko, which causes her to believe he is a mad machine.
Mitsuko then hires Hanpei Hattori and his apprentice Etsuko Sarutobi to find Jiro and bring him home.
Throughout the story, Jiro encounters robots and learns more about Professor Gill and the evil organization DARK.
Jiro is now battling to save Akira, the son of Professor Gill who survived and transplanted his brain into Hakaider.
Gill-Hakaider, supported by the Hakaider Squad and later SHADOW, targets Akira to power his giant-robot Armageddon Lord.
In the end, Gill successfully captures Akira, and uses the Armageddon Lord to devastate the city from the previous series.
Jiro leaves Akira in the hands of a monk scientist that raised Ichiro and reactivated Rei.
Afterwards, Jiro then proclaims that having now committed such horrible acts that he is now human and that his heart will forever be in "eternal conflict" as he walks alone into the sunset.