Colonel Kenji Doihara , Lieutenant Colonel Kanji Ishiwara , Colonel Takayoshi Tanaka and Major Seishirō Itagaki had completed plans for the incident by 31 May 1931 .
Until May 31 , 1931 , Colonel Kenji Doihara , Lieutenant Colonel Kanji Ishiwara , Colonel Takayoshi Tanaka , and Major Seishiro had completed Itagaki plans for the incident .