Issey moved on to higher education at Tokyo Imperial University and majored in mechanical engineering. Speaking on the background for the selection of his major, he said in later years, “I didn’t have any particular interest in machines. But a person with a mechanical background can find work at a research laboratory or other place in the city. And, I can always be immersed in the city atmosphere. That was the main reason I chose mechanical engineering.” However, since his brother-in-law had supported his school expenses, he studied diligently, partly with the spirit of returning the favor.

While he was attending the university, Issey met Dr. Ariya Inokuty, who was also from Ishikawa and who became his teacher. Issey later established the Inokuty Type Machinery Office to apply the theories of Dr. Inokuty to commercial businesses. At the time, Dr. Inokuty was in the Faculty of Engineering at Tokyo Imperial University, where he was known as an authority on hydraulics and applied mechanics and also conducted research on pumps. The principles behind pumps have been known since the time of the ancient Greeks, and were later developed further in Europe as equipment technology for irrigation.

Dr. Inokuty advanced his research while applying his own improvements and mathematical explanations, and in 1905 published the world’s first systematic thesis on centrifugal pumps, titled “Theory of Ordinary Centrifugal Pumps and of a New Centrifugal Pump having Divergent Vortex Chamber provided with Guide Vanes for producing Forced Vortex.”

Based on this theory, an experimental 180 mm turbine pump was manufactured and tested at the Shibaura Engineering Works of that time. It yielded results which were better than ever seen before in those days, with a pump head of 130 feet (39.5 m) and an average efficiency of 69%. These results were published in a paper titled “Result of a Forced Vortex Centrifugal Pump” which astonished many Western scholars.