Tobio Tenma was the young son of Dr. Tenma and Hoshie Tenma. Tobio was a bright young boy who was often set aside by his father in favor of his work. After Tobio was killed in a tragic accident, Dr. Tenma created a robot to replace him. That robot would later be known as Astro Boy.
Tobio obviously resembles a human version of Astro. However, where Astro has hair spikes, Tobio has natural cowlicks in his bangs and at the back of his head. He is generally portrayed with brown or black hair, and wears preppy, conservative clothing such as sweater vests.
In most series, Tobio is a smart but shy child. He was a clever student, but preferred staying at home or with his family members. Because Tobio's death is a major part of most Astro Boy series, not much is shown of Tobio's normal life, unless during Astro's origin story or via other characters' flashbacks.
Tobio's relationship with his father was strained. As the Minister of Science, Dr. Tenma had numerous responsibilities that kept him from away from home. Tobio had great respect for his father, but rued not being able to spend more time with him. In the 2003 series, Tobio was especially withdrawn at school and did not have very many human friends.
In the short film The Secret of Atom's Birth, Tobio remarks that his mother died of an "illness" when he was an infant and he never got to know her. Elsewhere in the manga's "Once Upon A Time" arc, Tobio's mother Hoshie was an active part of his life and took care of him.
Tobio appears in four manga segments about Astro's origin: chapters "Captain Atom" and "The Birth of Astro Boy", the “Once Upon a Time” arc, and in Atom Cat. Each time, Tobio's story is the same; Tobio tries to drive a toy car but is killed in traffic.
Tobio's backstory was the most expanded upon in the “Once Upon a Time” manga arc. The car Tobio was driving when he died was a toy car that Dr. Tenma bought him - similar to a Power Wheels toy vehicle - which Tobio decided to take onto the road.
When Astro is built and introduced to the Tenma household, Hoshie is at first unwilling to bond with the new Tobio. Astro eventually accidentally learns he is the robot replica of a human child, and at Astro's request, Hoshie tells him about her memories of Tobio: "Tobio spoke so fast that sometimes he'd get tongue-tied, and when he listened to me, sometimes he'd turn his eyes up a bit [...] When he walked he took big, fast strides. Sometimes he'd turn his head from side to side and shrug his shoulders a bit [...] When he changed his clothes...he wasn't very careful. He hardly ever folded them, and he tended to toss them on the floor. He didn't like his bath water very hot...and he often splashed around, kicking his legs." Astro attempts to emulate Tobio's behaviour until he accidentally breaks the bathtub.
The 1963 Astro Boy series has Tobio's most brief appearance. He is introduced in the first episode's opening scene, going for a joyride in his father's car. The English dub's narrator specifies that Tobio was allowed to drive a car because in "the futuristic year of 2000", driving a car was completely safe and all one had to do was "press a button". Unfortunately, Tobio's brakes malfunction and he is killed in a car accident. Dr. Tenma hears about this accident right away, and is so distraught that he comes to the site of the accident and carries Tobio's body away from the wreckage. After this, Dr. Tenma falls into a state of deep depression until he becomes inspired to create a robot that looks like Tobio.
The 1980 series opens with Skunk Kusai visiting Dr. Tenma at home, proposing the Omega Factor. Tobio and his beloved pet dog Jump listen in on the meeting. After the Omega Factor is rejected, Skunk leaves, but not before intimidating Tobio; he declares, "Kid, your father is really stupid!" Tobio runs into Tenma's office to reassure him, and as they talk, he gives Tenma the idea to make a child robot at the Ministry of Science.
Some days later, Dr. Tenma is busy working at the Ministry, and has unfortunately begun to neglect his son. Tobio is told their family trip to the zoo is postponed yet again, which makes him so upset that he decides to confront Tenma at the Ministry of Science himself. He boards a self-piloting mini-car to the Ministry but collides with a truck along the way. Later in the hospital, Tobio's dying wish to Tenma is to name the boy robot after him and "make it really cool and the strongest robot in the world."
In this series, Tobio is highly neglected, as his father Dr. Tenma is always busy. Dr. Tenma is always missing important moments in Tobio's life to the point where he has come to simply expect it from Tenma. Tobio did not have many friends in school, befriending his teachers instead of his peers, but he had a best friend in his robot tutor Robita. Most days, Robita was raising Tobio more than his own father was.
The true point of contention between Tenma and Tobio came when a new model of Robita robots was released. Tenma, regarding the Robitas as disposable appliances, offered to replace Tobio's Robita as a birthday gift. Tobio was revolted and argued with his father, soon realizing Tenma was so disconnected from his son that he was unaware of Tobio's bond with Robita. The argument ended with Tobio running out to the parking lot and leaving on his jet bike - a birthday gift from Tenma earlier that day. On the way out of the parkade tunnel, Tobio's bike collided with an oncoming truck, killing him instantly.
In the series present, Astro begins to have involuntary flashbacks of his surpressed past life as Tobio. One afternoon, a vision of Tobio appears before Astro and leads him to abandoned Tenma Manor. In here, Astro finds a discarded family photo of Dr. Tenma and Tobio, and Astro realizes he and Tobio are identical.
In the 2009 film, Tobio is 13 years old and more precocious than his earlier incarnations. He is highly intelligent, to the point where he completes and aces a school test in less than a minute, and he can even reprogram Orrin. Tobio is also quite confident talking back to President Stone and his guards. He goes against Tenma's orders to go home, instead sneaking into the Ministry of Science, which unfortunately leads to his untimely death.
After a mishap with the Red Core, the Peacekeeper goes berserk and discharges an ultra-powerful laser in the same room Toby has just been locked into. The only part of him that survives the blast is his cap and a single hair from Tobio's head; Tenma then uses this to restore Tobio's memories for his robot recreation.
- Tezuka, Osamu, trns. Frederick L. Schott. Astro Boy Volume 7. Dark Horse Comics, 2002. pg. 140
- Shin Tetsuwan Atom (1980), episode 1. Japanese dubbed version, English translation by Manga Entertainment.