The official language of Japan is Japanese (Nihongo), a Japonic language spoken by 128 million people in Japan, as well as by numerous diaspora communities around the world. Considered a pitch-tone language, half way between tonal languages and stressed languages, it features a complex system of honorifics which reflect the hierarchical nature of Japanese society.

The Japanese language is written with a combination of Chinese characters (kanji) and the Japanese syllabic scripts hiragana and katakana. Western-style Arabic numerals are generally used for numbers, but traditional Chinese/Japanese numberings are also commonplace.

A Latin alphabet known as romaji is also widely used to transcribe the sound of Japanese words for the benefit of non Japanese speakers, but there are many inconsistencies of spelling, particularly of vowels.

Japanese vocabulary has been heavily influenced by loans from other languages, with many words borrowed from Chinese, and more recently from western languages, primarily English.

Dozens of dialects are spoken in Japan, with two main dialectic regions - Eastern Japanese and Western Japanese - being identifiable. Standard Japanese (hyojungo) was based initially on Tokyo dialect, but the latter has since gone in its own direction to become one of Japan's many dialects.

The people of the Ryukyu Islands (including Okinawa) speak a tongue which, though considered a branch of the Japonic languages, is unintelligible to Japanese speakers.

The language of Hokkaido's Ainu ethnic minority, considered a language isolate with no known relationship with other languages, has been in decline for centuries and now has so few surviving speakers that it is in danger of falling out of use. However in recent years there have been efforts to reverse this decline.

English has become the language of business and tourism in Japan and its usage is increasingly promoted throughout the country at official level.