This paper discusses the new classification development in DDC (Dewey Decimal Classification) system for Japanese language book collection. It is based on most of library in Indonesia uses DDC system for classify all book collections, while notation of Japanese language books classification is not specified. Only one notation classification in Japanese language books (495.6), whereas Japanese language studies or topics is varied. This is different in Japan which uses NDC (Nippon Decimal Classification) with many notation (code) classification for each language category. Because of the library system not effective using 2 system, DDC system and NDC system can’t be use simultaneously.The purpose of this research is to expand Japanese language books notation in DDC system according to Taylor, Barwick, Sayers, and Hamakonda based on the criteria of good classification system. This research is expected to facilitate the library of universitas muhammadiyah and library in Indonesia to classify the Japanese language book. This research use descriptive method with qualitative approaches since analyzed descriptively with qualitative method. The method of analysis used evaluating DDC system as a library collection classification system, reviewing various topics or subject in Japanese language (linguistics), reviewing and to study the NDC (Nippon Decimal Classification) system related notation Japanese language books classification.