Hiro Yamamoto ( born April 13 , 1961 ) is a bassist who was a founding member of grunge band Soundgarden , along with Kim Thayil and Chris Cornell in 1984 . Hiro Yamamoto ( born April 13 , 1961 in Seattle , Washington ) is an American bassist who was a founding member of grunge band Soundgarden , along with Kim Thayil and Chris Cornell in 1984 .