We have updated Suzuki-kun, which is the prosodic reading tutor of Japanese that we developed as one feature of OJAD (Online Japanese Accent Dictionary). The original Suzuki-kun can visualize the prosodic and hierarchical structure of any given sentences to read them aloud in Tokyo Japanese and provide a synthetic speech sample based on the visualized prosody. The added new features are 1) generation of multiple speakers' voices, 2) speaking rate control, and 3) generation of dialogue speech among these speakers. Further, experimental results of examining the effects of Suzuki-kun on the naturalness of learners' spoken Japanese are described. It was found that visualized prosody is significantly more effective than auditory prosody. As of late August in 2017, 111 tutorial workshops of OJAD will have been given in 29 countries. In demonstration, teachers' reports will also be shown as well as Suzuki-kun's new features.