Syracuse was one of the leading architecture schools of the day and firmly rooted in the École des Beaux Arts pedagogy.
To fund his education, Tsumanuma purchased and operated a summer boardwalk shop at Sea Isle City, New Jersey called Nippon Bazaar.
While at Trowbridge & Livingston, he worked on the J.P. Morgan building at the corner of Wall and Broad Streets in New York City.
He was also principal designer for a besso (Japanese style country house) for Robert LeMoyne Barrett, in Concord, New Hampshire.
An early independent project of Tsumanuma's, obtained through his connections in New York's Nikkei community, was the Keizo Uenaka residence designed in the American Colonial style in Tokyo, Japan.
Under Tsumanuma's leadership, the most visible undertaking of the T-Square Club was a competition for the design of a Japanese style home suitable for American suburbs.
[9] By the end of the First World War, Tsumanuma and Shiota had accumulated an impressive portfolio of published projects, all of which incorporated Japanese design elements.
With the fashion for the Japonesque fading on the east coast, Tsumanuma made the first of two trips back to Japan in 1920 in search of new commissions abroad.
However, he returned from this trip with the largest and most complex project of his career, a 600-bed municipal hospital in Kobe, sponsored by Kawasaki Shipyards.
Tsumanuma was advised to take the rest cure at Saranac Lake, New York, the most advanced treatment available prior to the discovery of penicillin.