Ambassador Yoshikawa was born in Nara, Japan. In 1968, he studied for a year in high school in Le Roy, Illinois, U.S., on an American Field Service (AFS) scholarship. In April 1970, he entered International Christian University, College of Liberal Arts, Division of Social Sciences. While at ICU, he lived in Canada House and belonged to the judo club. In his senior year, he passed the Foreign Service Examination. After writing a senior thesis on the UN Peacekeeping operations, he graduated from ICU with a bachelor's degree in March 1974 and joined the Ministry of Foreign Affairs.
At the Ministry, he served, among many postings, as Minister and subsequently Ambassador for Political Affairs at the Japanese Mission to the United Nations, Deputy Director-General of the Economic Cooperation Bureau of the Ministry of Foreign Affairs, Director-General of the Middle Eastern and African Affairs Bureau, and then was appointed Ambassador to Spain in 2006. Later, he served as Japan's first Special Representative for Afghanistan and Pakistan, and then Ambassador and Permanent Representative to the OECD in Paris, where he served as Chair of the Executive Committee before assuming his present post at the Mission to the UN in September 2013.
Apart from English, he is fluent in Spanish and French.