By 1927, Ishii was advocating for the creation of a Japanese bio-weapons program, and in 1928 began a two-year tour of the West where he did extensive research on the effects of biological warfare and chemical warfare developments from World War I onwards. Ishii's travels were highly successful and helped win him the patronage of Sadao Araki, the Japanese Minister of the Army. Ishii also received the backing of Araki's ideological rival in the army, Major-General Tetsuzan Nagata, who was later considered Ishii's "most active supporter" at the Khabarovsk War Crime Trials. In January 1931, Ishii received promotion to Senior Army Surgeon, Third Class (surgeon major). According to Ishii's followers, Ishii was extremely loyal to the Emperor and had an "enthusiastic personality" and "daring and carefree attitude", with eccentric work habits such as working late at night in the lab after hanging out with friends at town. He was also known for his heavy drinking, womanizing and embezzling habits, which were tolerated by his colleagues.