noun
Japan expert; Japanologist; person knowledgeable about Japan
Refers to a non-Japanese person with deep knowledge of Japan, often used in academic or cultural contexts. The term is somewhat formal and not an everyday word.
彼は著名な知日家として、日本の文化を海外に紹介している。
As a well-known Japan expert, he introduces Japanese culture abroad.
その知日家は日本語が堪能で、日本文学にも詳しい。
That Japanologist is fluent in Japanese and also well-versed in Japanese literature.
親日家 means a Japanophile or someone who likes Japan, emphasizing affection rather than expertise.
Compound of 知 (chi, 'know') + 日 (nichi, 'Japan') + 家 (ka, 'person, expert'). The term likely emerged in the 20th century to describe foreign scholars and experts on Japan.