AI Engineer (Voice)

  • Tokyo
  • Partial Remote
  • Full-time
  • November 9, 2026
Conditions
yen-icon
¥6M ~ ¥9M /yr
location-icon
Apply from Anywhere 👍
visa-icon
Relocation to Japan 👍
(Overseas visa sponsorship supported)
Requirements
language-icon
Language Requirements
Japanese: Not Required 👍
English: Business Level
career-icon
Minimum Experience
Mid-level or above
yen-icon
¥6M ~ ¥9M /yr
location-icon
Apply from Anywhere
visa-icon
Relocation to Japan
language-icon
Japanese: Not Required
career-icon
Mid-level or above

We're looking for an AI Engineer to own HiKana's real-time voice conversation stack—speech recognition, TTS, LLM dialogue, and latency. HiKana is an iOS and Android app where English speakers practice Japanese by talking with Kana, an original AI anime character.

You'll work closely with our technical co-founder in a small Tokyo team, shipping improvements that learners feel immediately in every conversation.

 

Responsibilities

  • Design and improve real-time voice AI: ASR, TTS, turn-taking, barge-in, and end-to-end latency
  • Integrate and tune LLMs for spoken Japanese learning dialogue
  • Own reliability and quality metrics for live voice sessions on iOS and Android
  • Ship iteratively in a small, high-ownership team

 

Requirements

  • Strong English (required). Japanese is not required for day-to-day work
  • Genuine motivation to learn Japanese (required)—our product and users are built around that journey
  • Hands-on experience with real-time voice or conversational AI
  • Comfortable shipping production systems, not only prototypes
  • Based in or willing to work from Tokyo (Shibuya)

 

Nice to have

  • Japanese ASR/TTS or multilingual voice models
  • Mobile or realtime audio (WebRTC) experience
  • Interest in language learning or anime/IP consumer apps

90dS Inc. builds HiKana, an iOS and Android app where English speakers learn Japanese by talking with Kana, an original AI anime character.

Learners practice free voice conversation and real-world roleplay. Founded March 2025 in Tokyo (Shibuya) by Hayato Hoshikawa (CEO, formerly Google and Fanicon/THECOO) and Dan Jo (城 弾; co-founder, technical). Small team; also does AI/DX contract development.

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AI Engineer (Voice) at 90dS
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