Hiro Noshimuri was a corrupt business man with heavy ties to the Yakuza that appeared in Ke Kinohi (episode). Hiro is also responsible for the unintended death of Lieutenant Commander Steve McGarrett (2010)'s mother and the kidnapping of Mary Ann McGarrett, Steve's sister along with his brother, Kouji Noshimuri.
Eighteen years earlier, in 1992, Hiro Noshimuri was being tracked down by John McGarrett for his involvement in the Yukuza. The Yakuza wanted to keep Hiro undercover, so Kouji, Hiro's brother, put a bomb underneath John McGarrett's car. Unintentionally, his wife died instead.
Since that incident, Hiro had been under the radar until a grown Steve McGarrett arrested him for the kidnapping of his sister. However he was released from prison and kidnapped by Joe White for information on Shellburne and sent to an unknown place. His son Adam looked for him.
He reappeared in Pahele (Trapped) and was kidnapped by Joe White. He was held by Joe for a while before he and Joe worked to fake his death so his son wouldn't be targeted after their other accomplices were killed by Wo Fat.
He fled to Tokyo, Japan and remained there for an unknown amount of time prior to Ua Hopu (episode) but Adam later revealed to his girlfriend, Officer Kono Kalakaua (2010) that Hiro was actually dead, having been killed by Wo Fat who sent body parts to Adam.