Shin Ohashi (born 5 March 2009) is a Japanese swimmer specializing in breaststroke. At the 2026 Pan Pacific Swimming Championships, he broke his own junior world record to win silver in the 100 metres breaststroke. He also holds the junior world record in the 200 metres breaststroke.
He was named the 2025 Male World Junior Swimmer of the Year by Swimming World, for his performances including five medals at the 2025 World Aquatics Junior Swimming Championships. Ohashi became the Japanese national champion in all three breaststroke events at age 17, the youngest ever to do so.