(born April 13, 1961) is an American musician. He is a bassist. In 1984, he began the grunge band Soundgarden along with Kim Thayil and Chris Cornell. In 1989, he left the band after the completion of the Louder Than Love recording sessions.
Chris Cornell said about the recording of the album, "At the time Hiro had excommunicated himself from the band and there wasn't a free-flowing system as far as music went, so I ended up writing a lot of it." Yamamoto was becoming frustrated that he wasn't contributing much, and opted to go back to college. Cornell also said, "It seems an odd time to quit. We're doing real well. We've got a touring budget now. We don't haul amps or do such long van rides any more."
One year later, he started the independent rock band Truly with Screaming Trees drummer Mark Pickerel and Robert Roth from The Storybook Krooks.