A Shared Linguistic Heritage: The relationship between the Chinese and Japanese languages is one of the most unique in the world. The Japanese writing system, Kanji, is directly derived from Chinese characters (Hanzi). This means a Chinese speaker can often get the general gist of a Japanese newspaper headline without knowing any Japanese grammar. For a learner, this shared script is both a blessing and a curse, as some characters have evolved to have different meanings. 日语, therefore, isn't just a “foreign” language to Chinese speakers; it's a “familiar” foreign language with deep historical ties.
The “Country + Language” Pattern: Understanding 日语 (rìyǔ) unlocks a fundamental pattern in Chinese for naming languages: `[Country Abbreviation] + 语 (yǔ)`. For example, 英语 (Yīngyǔ) is English (from 英国 Yīngguó), 法语 (Fǎyǔ) is French (from 法国 Fǎguó), and 汉语 (Hànyǔ) is Chinese (from 汉 Hàn ethnicity). This makes learning the names of other languages much easier.
Pop Culture Influence: In modern China, Japanese pop culture, especially anime (动漫 dòngmàn), has a massive following. Young people often learn basic 日语 phrases from their favorite shows, and the term 日语 is frequently used when discussing voice actors, original audio, or fan translations.