Aonomo is an unseen character mentioned in Dead Island. He is a contact of Roger Howard's, who agreed to inform Roger on the illegal activities occurring on Banoi. He is mentioned in one of Roger's recordings, in which Roger finds that Mr. Aonomo's house has been overrun by zombies.
Not much is known about Mr. Aonomo, since he's not seen in-game or in any other Dead Island media. Since Mr. Aonomo has information on the illegal activities, it's likely that he worked for a large, well known business or for the Banoi government. It's also possible that he worked for the Royal Palms Resort, where it would be relatively easy to overhear anything shady happening.
He agreed to help out Roger Howard conduct an investigation into the goings on on Banoi by giving him vital and important information about the illegal activities happening, such as logging, clear cutting and even money laundering happening at the Royal Palms Resort. However, when Roger reached Mr. Aonomo's house somewhere in the Resort, he found it taken over by zombies. While Roger didn't see Mr. Aonomo's body in the house, he heard a noise deeper in the house after he clubbed a zombie to death which might have been made by Mr. Aonomo, but he didn't wait around to find out, leaving Mr. Aonomo's fate unknown but likely undead.