Me too! I couldn't find one so I cobbled one together. I wrote enough python for all the parts to work together. I can speak Japanese into it, it gets recognized, and - all too eagerly - the chatbot corrects my mistakes.

My stack, running locally on a Windows 10 machine: - Vosk STT augmented with vosk-model-ja-0.22 for Japanese - Gemma4 LLM running in Ollama and with customized model card to act as a Japanese tutor - Kokoro TTS using Japanese voice jf_alpha.pt and augmented with the unidic Japanese dictionary