[1] He attended Tokyo Imperial University Medical School and, upon graduation in 1911, joined the staff of Sugamo Hospital (present-day Tokyo Metropolitan Matsuzawa Hospital) where he began his study of psychiatry.
[3] Mokichi studied tanka under Itō Sachio, a disciple of Masaoka Shiki and leader, after his master's death, of the Negishi Tanka Society; Sachio also edited the society's official journal Ashibi.
[4][5] This magazine, due to Sachio's increasing commitment to other literary activities, was subsequently replaced by Araragi in 1908.
Mokichi was the family doctor of author Ryūnosuke Akutagawa and may have unknowingly played an indirect role in the latter's suicide.
[14] He also wrote philological essays on waka of Kakinomoto no Hitomaro and of Minamoto no Sanetomo.