The Tokyo Bar Association selected Hideko Hakamata, the elder sister of former death-row inmate Iwao, to receive its human rights award.
The association said Friday that it recognized the 91-year-old sister's decadeslong efforts to save her brother and her work to eradicate wrong accusations and convictions.
Iwao, 88, was acquitted in a retrial earlier this year, decades after he was convicted over the 1966 murder of four people in Shizuoka.
"I'm at a loss because I've never received an award," Hideko told a video news conference. "I didn't do this alone. I'd like to thank everyone across the country once again."
She pledged to do all she can to open the door for retrials of other wrongly convicted people.
Hideko said Iwao has been taken for a drive every day. "I want to help him live a long time," she said.
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