In first encounter situations, Japanese speakers usually choose the polite form as the basis for their conversation. In the case of Japanese learners, however, it is often observed the use of plain form in these situations. This research analyzes the use of plain form in speech of 90 learners whose mother tongue are Korean, English and Chinese produced in first encounter situations. All the speeches were collected from the KY corpus. In this article, we will show some of the results concerning the Chinese learners. Two main points were considered in the analysis of plain form in the learners’ speech: (a) interference of Chinese modal particles; (b) acquisition of speech organization competence. As for (a), we must mention that the so called “modal particles” in Chinese have similar functions to the sentence-final particles in Japanese, both playing an important role in face-to-face interaction. In Chinese language, there is no clear distinction between sentence-final particles and interjection particles. This may partially explain the use of ‘yo’ with functions other than this particle’s original constraints observed in Japanese speakers’ speech. Also, the subjects used ‘na’, ‘ne’ and ‘yo’ as a strategy to display affinity and to soften the tone of the speech. (b) It was observed a progression from listing of simple sentences toward production of complex sentences. While the polite form was used as a marker of speech organization, plain form was used as a marker of topic organization. The Chinese subjects tended to use the plain form while talking about the same conversation topic and the polite form to bring the conversation of this topic to an end.