After graduating from the University of Tokyo, he became a prosecutor, and served in several assignments, including as Legal Attache to the Embassy of Japan in the United States of America.

Yamashita left government service in 2010 after serving in an international director role in the Ministry of Justice.

[2] Opposition parties submitted a no confidence motion against Yamashita in November 2018, alleging that he did not properly explain an immigration bill that would admit more foreign workers to Japan.

[3] Nissan chairman Carlos Ghosn was arrested and jailed during Yamashita's tenure as Justice Minister.

[4] After Yamashita stepped down as Minister of Justice in September 2019, he was appointed as chief secretary of the LDP's internal body on revising the constitution, led by Hiroyuki Hosoda.