Kotaro Honda (本多 光太郎, Honda Kōtarō, born on February 23, 1870 in Okazaki, Aichi Prefecture – February 12, 1954) was a Japanese scientist and inventor. He invented KS steel (initials from Kichiei Sumitomo), which is a type of magnetic resistant steel that is three times more resistant than tungsten steel. He later improved upon the steel, creating NKS steel. The NKS steel was mentioned by Taiichi Ohno in his book, as being one of the Japanese materials development results after the Second world war. He was awarded the Culture Award and the Big Asahi Ribbon of the First Class. He was taught by the famous Japanese physicist Hantaro Nagaoka at the University of Tokyo. He was one of the first persons to be awarded the Order of Culture when it was established in 1937, being conferred with the honor in 1951. He was posthumously awarded the Grand Cordon of the Order of the Rising Sun. He participated in establishing the (千葉工業大学, Chiba Institute of Technology) from 1940.