Kanji are the Chinese characters that are used in the modern Japanese writing system along with hiragana (ひらがな, 平仮名), katakana (カタカナ, 片仮名), Indo Arabic numerals, and the occasional use of the Latin alphabet (known as the Romanization of Japanese, or "Rōmaji").

The Japanese term kanji (漢字) literally means "Han characters" or "Chinese characters" and is the same written term used in the Chinese language to refer to the character writing system. Chinese characters also came to be used to write Japanese words, resulting in the modern kana syllabaries. A writing system called man'yōgana (used in the ancient poetry anthology Man'yōshū) evolved that used a number of Chinese characters for their sound, rather than for their meaning.

Man'yōgana written in cursive style evolved into hiragana, a writing system that was accessible to women (who were denied higher education). Katakana emerged via a parallel path: monastery students simplified man'yōgana to a single constituent element.

The two other writing systems, hiragana and katakana, referred to collectively as kana, are actually descended from kanji.