Mr. Ekuan’s aesthetic drew on classical Japanese forms as well as Western influences. His family owned a well-known Buddhist painting depicting heaven and hell, which it displayed at the temple in Hiroshima just one day a year. It was destroyed by the bomb along with the temple, but it remained “one of my design ideals,” Mr. Ekuan wrote in his memoir.

Image A bottle of Kikkoman soy sauce.

He also read “Blondie” comics and admired American inventiveness. The G.I.s in Japan after the war, with their Jeeps and pressed gabardine trousers, were like a “moving exhibition,” he told The Times. At the National University of Fine Arts and Music in Tokyo, where he enrolled in 1950, he encouraged his fellow students to give shape to a contemporary “Japanese lifestyle.”

Mr. Ekuan won the soy sauce contract, from the Kikkoman Corporation, while still in his 20s. It took him three years and 100 prototypes to come up with a final design for his dispenser, which combined a gracefully curving form with an innovative, dripless spout. More than 300 million of the bottles have been sold.

Mr. Ekuan’s contribution to the bullet train network was a lean, long-nosed version called the Komachi, which began running on the northern Akita Shinkansen branch line in 1997. He also designed the Narita Express shuttle trains that ferry passengers between Tokyo and Narita International Airport.

Mr. Ekuan often worked with advanced technology, but he disliked futurism for its own sake. “When we think of the evolution of design, we might imagine a world where robots are everywhere, but that’s not it,” he told Cinra.net, an online design magazine, in 2013. “The ultimate design is little different from the natural world.”

Kenji Ekuan was born on Sept. 11, 1929, in Tokyo. When he was a year old, he moved with his family to Hawaii, where his father worked as a Buddhist missionary. They returned to Japan when Kenji was 7. He is survived by a brother and a sister.