Modern Japan is resolutely turning towards creating a full-fledged multicultural society. Becoming aware of the depopulation crisis, many municipalities are actively working to attract foreigners. In combination with other measures of the Japanese government, teaching Japanese to foreigners of all levels ensures mutual understanding. The concept of “Plain Japanese” (PJL) implies the use of a simplified language with limited vocabulary and a set of elementary grammar. “Plain Japanese” was created as a means of providing information to foreigners, firstly for emergency situations, and secondly for everyday life. The scope of application of “Plain Japanese” over the past 25 years has expanded considerably. The leading role in the study of “Plain Japanese” belongs to the research team of Professor Iori Isao from Hitotsubashi University (Pref. Tokyo). Prof. Iori believes that “Plain Japanese” can perform the following key functions: 1. “Plain Japanese” as a state guarantee of “compensatory education”. Children of foreigners who grew up in Japan should also be able to socialize unhindered. “Plain Japanese” is suitable for this purpose as well as possible. 2. “Plain Japanese” as a language of communication in regional communities. In order for “Plain Japanese” to successfully perform the role of an intermediary language, not only foreigners should speak and study it, but also the Japanese who work with foreigners. 3. “Plain Japanese” as the initial level of the Japanese language across all regions. These are schools and Japanese courses for foreigners. To teach the initial level of the Japanese language in a very short time, it is necessary to considerably cut down the grammatical and lexical minimum compared to, for example, the school course of the Japanese language. At present, digital technologies have been created for translating texts to the European Congregation Campaign, research groups are being conducted, and educational literature is being produced by initiative groups.