Noriko Noshimuri

Noriko Noshimuri was the secret daughter of Hiro Noshimuri, and the younger sister of Adam Noshimuri. She was the main antagonist of Season 8 and was nicknamed "The Ghost".

Season 8
Noriko was behind the murders of Agent Fisher and all of the crime bosses on Hawaii. She recruited an FBI agent to bring in her brother Adam Noshimuri and frame him for Hideki's death.

In No One Has Ever Died For the Mistakes He Has Made; Only Because He Didn't Repent, she had Agent McNeal bring in Adam and then killed the agent. She asked Adam for Michelle Shioma's $20 million, threatening to order a hit on Kono Kalakaua, Chin Ho Kelly, Abby Dunn, and Sara Diaz. He reluctantly agreed. Together with Jessie, Adam picked up the money from Mr. Kimura, a Yakuza banker, but Jessie betrayed him and fled with the money. She is later found dead, presumably killed by Noriko.

In the next episode, Kind Is the Bird of Kaiona, Noriko’s body was washed up on the shore with a gunshot wound in the back of the head.

In The Tough Branch That Does Not Break in the Kona Gale Tani found a gun in Adam's apartment that she suspected to be the weapon with which Noriko was killed. She wondered if Adam had killed Noriko, given that she had threatened his family and he had said that prison would be “too good for her”.

Season 9
In The Man Who Fell from the Sky, Tani asked Captain Keo, her former instructor at the HPD, to check if the weapon she had found in Adam’s house was connected to any crimes since she did not want to share her suspicion with Steve before she had proof of Adam’s guilt. Keo called her in Nothing More the Eyes to Search For and told her that Noriko was shot with this weapon.

However, it was revealed in Truth Comes from the Night that Mr. Kimura had killed Noriko and tried to frame Adam.