Dr. Hirai is Board Certified by the American Board of Surgery, and is Fellowship trained in Minimally Invasive and Bariatric Surgery. He is also a Diplomate of the American Board of Obesity Medicine.

He performs a wide range of General Surgery procedures, and his interests include the treatment of breast diseases, hernias, reflux disease, GI diseases such as colon and stomach cancer, and the treatment of morbid obesity. Among other Bariatric procedures, he has been performing the Sleeve Gastrectomy since 2005, and was the first to perform a Robotic Bariatric operation in San Jose.

He has been involved in teaching, including the training of Minimally Invasive and Advanced GI Surgery Fellows from the Palo Alto VA/Stanford University Fellowship Program.

He speaks several languages, including English, Portuguese, Spanish and Japanese.

He provides compassionate and individualized care, and has been listed as a top doctor in the San Francisco Bay Area by Castle Connolly and the San Francisco Magazine.