Some say that the tamagotoji katsudon was invented by Keijiro NAKANISHI who was a student of Waseda University in 1921, while others believe that it was the invention of the owner of a soba restaurant Sanchoan located in Babashita-cho, Shinjuku Ward.
1921年に早稲田大学の学生・中西敬二郎が考案したという説や新宿区馬場下町の蕎麦屋三朝庵の店主が考案した説がある。