Since his teenage years, Koji Hayashi has dreaded one thing: his stubborn, once-vivacious mother being hanged for murder after failing to win her long campaign for a retrial.

Left almost unchanged for a century, Japan's current retrial system is often labelled the "Unopenable Door" because the chances of being granted a legal do-over are so slim.

But hopes have grown of a change since a court last year overturned the wrongful conviction of the world's longest-serving death row prisoner Iwao Hakamada, whose case took 42 years to be reopened.

The government is asking legal experts to study the system, and some hope they will recommend revising the arduous retrial process to better safeguard the interests of convicts like Hakamada.

Masumi Hayashi, 63, is notorious in Japan for a crime she swears she didn't commit -- killing four people by putting arsenic into a pot of curry at a summer festival in 1998.

Koji isn't entirely convinced his mother is innocent, but "I think there's a good chance", he told AFP.

"All I want is the truth, and a retrial is the only way to get it," the 37-year-old truck driver said.

Since the Supreme Court upheld her death sentence in 2009 Masumi has applied for retrial several times, with her latest bid........

© International Business Times