Nanae Aoyama was born in Saitma Prefecture, Japan. She graduated from the School of Library and Information Science at the University of Tsukuba. In 2007, she was awarded the Akutagawa Prize, the most prestigious Literary Award given to young authors, for Hitori Biyori, and in 2009 she became the youngest recipient of the Yasunari Kawabata Literary Prize, for the best short fiction of the year, for Kakera.
Satoe Tone was born in Fukui Prefecture, Japan. After studying Design at Kyoto Seika University, she became a published children's picture book author in 2011 while residing in Milan. In 2013, she was awarded the International Award for Illustration at the Bologna Children's Book Fair in 2013.