- He was born in 1896 in a merchant family, during a time when class was very important even in modern Japan. Because the Miyazawa family was viewed with distrust and envy by the surrounding farmers, it was both a blessing and a curse to Kenji. All his life, he struggled to come to terms with the disparity between his own circumstances and those of the poorer farmers.
- As a young boy, Kenji was an avid rock collector. Later on, he was enrolled in Morioka Agriculture and Forestry Higher School (an equivalent of graduate school), which gained him an education in soil science. He was nicknamed "Rocking Ken" precisely for his love of rocks.
- He quarreled with his father often over his future. Kenji was to inherit the family pawn shop, but he knew the business was not for him. His father would not agreed to anything else, however, until one day he hopped on a train to Tokyo to follow his religious calling. It was during this time that he wrote many of his children's stories, sometimes three thousand manuscript pages per month. His stay was short-lived, however, as he was recalled back home because of the deterioration of his sister's health.
- Although Kenji is most famous for his free verse and children's stories, he wrote thirty-one syllable tankas for nearly ten years of his life, first out of admiration for Ishikawa Takuboku and Kitahara Hakushuu, and later for a literary magazine in college.