According to the commission, Kato's accident was caused by sudden braking….

Kato, the commission ruled: "It was not the fault of
motorcycle"

"We are certain that he lost control of the motorbike due to a sudden crash
braking"

Daijiro Kato, the Japanese rider who perished in the first MotoGP race
2003 on the Suzuka circuit on April 3rd, he would have died for a series
of circumstances linked to probable pilot `errors` and poor disposition
of barriers along the circuit, while character problems would be excluded
mechanical however related to the motorbike. A commission of inquiry established this
independent company formed by `Honda Corse`, the same company he raced for
the Japanese pilot.

Ichiro Kageyama, head of the investigative commission and technology teacher
industrialist at Nihon University in Tokyo, said: "We are
almost certain that Kato has lost control, in all likelihood
due to a sudden, delayed braking of his motorbike... until he was thrown out of the saddle
the pilot, who violently hit his head perpendicularly against barriers
of foam rubber… In another situation, the accident perhaps would not have occurred
deadly consequences."
The commission then recommended that the Suzuka circuit be judged poorly
sure by many pilots, is improved especially with regards to
arrangement of barriers.

Source: Tgcom.it