This paper discusses several design issues in the development of a new online Japanese textbook, called "Robo-Sensei: Japanese Curriculum with Automated Feedback". When it is completed, the new online textbook will present a full Japanese curriculum. It extends a previously published online software program, "Robo-Sensei: Personal Japanese Tutor" (Nagata, 2004), which was designed as a supplement to standard, printed Japanese textbooks. The issues discussed include incorporation of natural language processing (NLP) technology, visual images, sounds, grading, modular organization, and classroom activities. Special attention is devoted in this paper to the design of a stand-alone module for teaching Japanese characters, called Kana Power. Student evaluations of the Kana Power module are discussed. Throughout the paper, the potential advantages of online versus printed textbooks are emphasized. (Contains 9 figures and 2 notes.)