He served as Lord Keeper of the Privy Seal of Japan (1936-1940), Minister of the Imperial Household (1933-1936), Inspector-General of Korea (1925-1927) and President of the Board of Audit (1929-1933).

The Ishikawa family had been doctors and prominent village headmen of Uka for generations; Ishikawa's eldest daughter Tomoko had married Prime Minister Yamagata Aritomo in 1867, and the family was later involved in the management of Mitsui Bank and served as mayor of Shimonoseki.

Kurahei's family moved to Kōriyama, Fukushima Prefecture after his elder brother Tamenoshin opened a hospital there.

He succeeded as Lord Keeper of the Privy Seal of Japan on March 6, 1936, after Saitō Makoto was assassinated during the incident.

On June 1, 1940, Yuasa was forced to resign as Lord Keeper of the Privy Seal of Japan due to his deteriorating health.

[4] His nephew Daitarō Yuasa was Director of Jusendō Hospital and helped establish the Kōriyama City Library.