Japanese artist and children’s book author-illustrator Mitsumasa Anno, known for his highly detailed illustrations containing visual tricks, humorous elements, and math concepts, died on December 24. He was 94.

Anno was born March 20, 1926, in Shimane Prefecture, in western Japan. He grew up in Tsuwano, a small town surrounded by mountains, where his talent for drawing and an aptitude for mathematics began to shine, and where his dream of becoming an artist first took root.

In a 1983 Horn Book interview, Anno noted that even as a young boy he had always longed to journey beyond the isolation of his small community. “Because my world was cut off from the outside world, first by the mountains and then by the ocean, the desire to go and see what lay on the other side grew stronger,” he said. Anno got his first opportunity to leave home and explore when he attended a regional high school where he studied art and drawing. He would later document impressions of his life’s travels in the Journey Book series of wordless picture books, including Anno’s Journey, which featured images inspired by his 1963 trip to Germany, England, and Scandinavia; Anno’s Italy; and Anno’s USA.

Anno served in the Japanese army during WWII. After the war he studied at Yamaguchi Teacher Training College, earning his degree in 1948. He taught math at a Tokyo elementary school for 10 years and during that time developed creative ways to present material to his students using different perspectives. Anno continued working on his art in his spare time until he fully launched his career as a painter in 1961.

Anno’s passions for mathematics, science, and depicting varying perspectives would all serve as inspiration for his picture books, beginning with Topsy-Turvies: Pictures to Stretch the Imagination (Weatherhill, 1970) Upside Downers: More Pictures to Stretch the Imagination (Weatherhill, 1971) (like all of Anno’s work, these books were originally published in Japan before being released in translation in the U.S.). Anno’s Alphabet: An Adventure in Imagination (Crowell, 1975) became a phenomenon in Great Britain, and was so popular that it was being considered for the Kate Greenaway Medal in 1974, until the judges learned that the book was originally published in Japan by a Japanese author and was not eligible for the award. Critics praised Anno’s Mysterious Multiplying Jar (Philomel, 1983) for its “clever” and “deceptively simple” portrayal of the concept of factorials. Anno’s Magic Seeds (Philomel, 1994) presented a history of agriculture and conservation intertwined with math games.

Throughout his career, Anno received numerous honors, citations, and awards for his work internationally, including multiple first prizes for graphic excellence at the Bologna Children’s Book Fair, and having his books selected for the New York Times Best Illustrated Books of the Year list. In 1984 he received the prestigious international Hans Christian Andersen Medal, which honors authors and illustrators who have made lasting contributions to children’s literature. His art has been exhibited at major galleries and museums in Japan, Canada, Great Britain, and the U.S., and in 2001, the Mitsumasa Anno Museum—designed by the artist himself—was established in his honor in his hometown of Tsuwano. At that time, Anno’s longtime U.S. editor, Ann Beneduce, told PW that Anno is “as popular as a pop star. People from all over the country will travel to this museum.” Beneduce added, “He really wants his museum to be a place where children can come in and try things. He has always been very interested in science and math and in introducing these subjects to kids in an enjoyable way. He sees his museum as an opportunity to do just that, and has even included a planetarium as part of the building.”

Reflecting on the many years when she and Anno worked on projects together, Beneduce shared these words of tribute with PW: “Anno was a great artist and a great friend. He once stayed in our house and made sketches of dung beetles. I also visited him and his museum in Japan, where he was a national treasure and great host.”