Short answers, pulled from the story.
Tadahito Mochinaga served as an assistant to Seo Mitsuyo on the 1943 animated propaganda film Momotarō's Sea Eagles. He was officially in charge of backgrounds and visual effects for this project depicting the bombing of Pearl Harbor.
Tadahito Mochinaga fled with his pregnant wife to Japan-occupied Manchuria shortly after the war began. There, he got a job at Man-Ei as a graphic artist before being rehired at the rebranded Northeast Film Studio following the Japanese surrender.
Tadahito Mochinaga built puppets and shot them frame-by-frame instead of live to save scarce paint and unexposed film in 1946. This method became a resounding success and popularized stop motion in China among many who remembered attending puppet shows.
Tadahito Mochinaga returned to his home country in 1954 after working in China for nearly a decade. Four years later in 1958, massive famines occurred in Japan while he had already established himself back home.
Tadahito Mochinaga worked on Rudolph the Red-Nosed Reindeer released in 1964 and Willy McBean and his Magic Machine followed in 1965. He also contributed to The Daydreamer in 1966, Ballad of Smokey the Bear in 1966, and Mad Monster Party? marked another significant collaboration in 1967.