When Kumagusu moved to Tanabe in 1904, he continued his rough lifestyle, drinking every day for example. His friend Kitahaba Takesaburō worried for Kumagusu and decided to let him marry to Tamura Matsue, the daughter of the chief priest of a Shinto shrine.
In 1906, they were married, and the following year, they had their first child, a son named Kumaya. Kumagusu wrote in his diary of the joy of becoming a father when having seen his son for the first time, and he made detailed observations of Kumaya’s growth.
Their daughter Fumie was born in 1911.
In 1925, Kumaya became sick and was not recovered rapidly. Around this period, Kumagusu’s relationship with his brother Tsunegusu worsened. Burdened with medical expenses, their lives became difficult.
His daughter Fumie, along with Matsue, came to help Kumagusu with his research until his later years.