is a Japanese race walker.
Yamanishi won a gold medal in 20 kilometres race walk at the 2019 Asian Race Walking Championships in Nomi, with a World Leading time of 1:17.15 (2019 season).
At the 2019 and 2022 World Athletics Championships, Yamanishi won the gold medal in the 20 kilometres walk event, consecutively in 2019 and 2022.
On 16 February 2025, Yamanishi won the Japanese 20 kilometres Race Walking Championships with a new world record of 1:16:10 to break the previous record of 1:16:36 set by Yusuke Suzuki in 2015.