Less than a year later, after having contracted the beriberi, Morihei had to leave Tokyo and returned to his hometown of Tanabe for treatment. The same year he married Hatsu Itokawa (born 1881), a distant relative he knew since his childhood.

Learning from his adventure in Tokyo, the young Morihei had realized that he was not made for trade. Infatuated by the adventures, he decided in 1903 to enlist in the army, which was recruiting to meet the need in men.

First they refused him because he was too small. Mortified, Morihei tied a heavy weight to his legs and hung on a tree branch for hours to lengthen his spine. Finally, he was enlisted in the 37th Regiment of the fourth division of Osaka .

His great skill in martial arts was revealed during training with the bayonet in which he proved to be a particularly soldier. So they gave him the nickname " God of the soldiers " because of his great skill in bayonet and Juken -Jutsu and also because of his determination to work and his honesty.

In 1904 he was sent to the front during the Russo-Japanese War and returned with the rank of sergeant.