Southwest Japan high schoolers win contest after inventing device to cut cake equally

KUNISAKI, Oita -- Inspired by fierce family battles for the last remaining piece of cake, a team of three high schoolers in southwestern Japan's Oita Prefecture have invented a device that cuts round cake and pizza evenly, no matter how many pieces are sliced, and their creation won the top prize in the prefecture's invention contest in 2021.

The three students belong to the industrial technology club at Oita Prefectural Kunisaki High School. Their clever invention to solve a daily life problem with a flexible mindset won the governor's award in the competition and is gathering attention.

Twelve students in the electronics department of the school belong to the industrial technology club, which has continued to submit works to the invention contest for about 40 years. Five of their creations won prizes in the high school division of the 2021 edition of the competition that was launched in 1941.

The top prize-winning device, whose name translates to "Let's kindly divide it up," was invented by second-year students Wataru Onoda, 16, Rinto Kimura, 17, and third-year student Mitsumi Zaizen, 18. It was inspired by battles for birthday cake in Onoda's family. He needed to defeat his rival two sisters in games of rock-paper-scissors to get the last remaining piece because the cake was always cut into eight pieces despite his family having seven members.

Based on Onoda's idea to equally divide a cake into seven pieces, Kimura created a drawing and computer program to precisely make parts for the device. While Zaizen could not be involved in the actual production due to preparations for her university entrance exams, she created a video for the presentation, utilizing her experience of winning a prize in the competition for two years in a row.

After a two-month trial and error process, the device was completed. When a cake or pizza is placed on a turntable made with a laser beam machine, it can be cut evenly into the desired number of pieces along the laser light. For example, to serve five people, a cake or pizza is cut at 72 angular degrees each. The process is also hygienic because no one has to touch the food.

In an October 2021 jury review, the creation of the device was highly evaluated for reasons including its innovation enabling users to cut food in a fair manner even for an odd number of people.

Kimito Kotani, the executive director of Oita Prefecture Institute of Invention and Innovation, which organized the competition, praised the work, saying, "They solved an inconvenience in our daily lives while enjoying the process."

Onoda is pleased about their invention and said, "We will not have any more cake problems."

Meanwhile, Kimura commented, "It was difficult to form the shape to put the required functions into a limited space."

Zaizen, who gained self-confidence from the project and will start studying at a university in April, said, "Our flexible idea was highly evaluated."

Shinji Matsuda, the club's adviser and practical teacher, added, "Receiving high evaluations for an invention that students passionately worked on has boosted their confidence and increased their career options." He said that he will continue to support them from a technical aspect.

(Japanese original by Yuki Imano, Kyushu News Department)