Hirokazu Yasuhara (安原 広和, Yasuhara Hirokazu, born October 12, 1965) (also credited as Carol Yas) is a Japanese video game designer. He is best known for designing the gameplay and stages of the initial Sonic the Hedgehog video games for Sega Genesis in the 1990s, based on technical demos and engines programmed by Yuji Naka. Yasuhara stayed with Sega until the late 1990s. He then joined Naughty Dog, working on the Jak and Daxter series and Uncharted: Drake's Fortune, collaborating again with former Sega employee Mark Cerny. He was the senior design director at Namco Bandai Games America. In April 2012, Yasuhara joined Nintendo where he accepted a position at the Nintendo Software Technology division. He has since worked for Unity Technologies.