1960's TV series
Tobio is seen in the first episode, going for a joyride in his father's automobile. He was not supposed to be doing this because he was too young to drive, also he did not ask for his father's permission. Tobio is involved in a horrible car accident and is killed. When Dr. Tenma heard about that and he came to the site of the accident in tears and held Tobio's dead body in his arms. After this Dr. Tenma falls into a state of deep depression but he later creates a robot that looks like Tobio and has the memories of the original Tobio, that robot is Astro Boy. Tenma treated Astro Boy as if he were his real human son and loved him like he was his real son but later abandons Astro at a robot circus after realizing he was not his real son.
1980's TV series
In this series the story is somewhat different, it begins with Tobio going to see his father at the Ministry of Science, instead of Tobio driving in an automobile. Tobio wants his father to drive him around the city for fun but he neglects Tobio and says he is too busy for him right now, Tobio is hurt by this and leaves the ministry to drive the car by himself. He is too young to drive and is inexperienced, his driving goes out of control and he accidentally crashes into a truck and is killed. Dr. Tenma mourns over the loss of his beloved son. Like in every version of the show, he creates Astro Boy. In this version he did not abandon Astro he was separated from him while on a cruise ship.
2003 TV seriesThe story in this version is somewhat different from the other versions. In this version, Tobio was close friends with a robot tutor that Tenma had built to educate him. But, Tenma later deactivated that robot to build newer models, and Tobio became upset with his father about this. While Tenma and Tobio were at the ministry they had an argument about this and Tobio ran from his father and rode on his new jetbike that his father bought him until he crashes into oncoming traffic inside a tunnel. After his death, Tenma was heart broken and blamed himself for his son's death, but then he created Astro Boy. However, Tenma went insane sometime after this and deactivates Astro along with his other robots. Astro Boy is later reactivated by Dr. O'Shay.
Toby, after sneaking in the room where Dr. Tenma and Oshay were demonstrating 'The Peacekeeper' using the power of blue and red cores, is soon trapped behind a emergency glass separating the scientist from danger. But is soon killed when 'The Peacekeeper' unleashes a deadly force to destroy the glass shield.