We have raised USD 11.83 million (≈ JPY 1.7 billion) in a Seed 2 round to accelerate commercialization
Top Japanese venture capital firms and US–Japan angel investors back the company, accelerating commercialization of real-time speech-generation AI and ramping up hiring.
Kotoba Technologies, Inc.—a Seattle-based startup with a Tokyo office that is pioneering state-of-the-art real-time speech-generation AI—announces that it has closed a USD 11.83 million (≈ JPY 1.7 billion*) Seed 2 round as of 30 June 2025.
The round was led by Globis Capital Partners and Boost Capital, together with SIP Capital (which led the Seed 1 round), and a group of angel investors that includes Joi Ito (Co-founder of Digital Garage and former Director of the MIT Media Lab), Thomas Wolf (Co-founder & CSO of Hugging Face), Toru Shimada (former President & Owner of the Tohoku Rakuten Golden Eagles), Luke Zettlemoyer (Research Manager at Meta Platforms and Professor at the University of Washington), and Noah Smith (Senior Director of NLP Research at the Allen Institute for AI and Professor at the University of Washington).
* Converted at USD 1 = JPY 144.
Background to the financing
Guided by the mission “to build and deliver cutting-edge real-time speech-generation AI to the world,” Kotoba Technologies is developing proprietary speech-generation models from a unique perspective. The founding team—both PhDs with first-rate AI research credentials—has attracted top-tier researchers and engineers from around the globe.
Including the USD 1.5 million Seed 1 round led by SIP Capital, total funding now stands at USD 13.33 million (≈ JPY 1.9 billion).
The new capital will be invested in hiring machine-learning and application engineers to advance model development and productisation, as well as building a business organisation that will accelerate the transition from R&D to commercial rollout.
Accelerating the path to commercialisation
Kotoba’s simultaneous-interpretation iOS app, “Simultaneous Interpreter – A New Frontier in Real-Time Speech Translation,” has logged almost 500 thousand user sessions within three months of launch. Major media outlets such as TV Tokyo and Abema Prime have highlighted the app as offering “world-leading” AI simultaneous interpretation.
Upcoming releases will extend the current speech-to-text capabilities to natural, fluent speech-to-speech translation in real time. In addition to mobile, the company is preparing paid versions that support desktop use.
Kotoba is also preparing to expose its advanced speech-AI technology via APIs for enterprises and developers—starting with ASR (automatic speech recognition) and other building-blocks for voice agents—scheduled to roll out sequentially from the end of July 2025.
New Chief Business Officer
To speed up commercialisation, Yusuke Shimomura will join Kotoba as Chief Business Officer in July 2025. At PKSHA Technology he launched the dialogue-AI and voice-AI businesses, served as Executive Officer in charge of Product Businesses, and was President of a subsidiary—bringing deep experience in scaling AI ventures.
Profile – Yusuke Shimomura
After starting his career at Accenture in data analytics for financial clients, he joined PKSHA Technology in 2015. As business lead he created the PKSHA Chatbot business (the prototype of PKSHA’s AI SaaS line), expanding into customer support and internal-help-desk domains. In 2018 he launched the PKSHA Voicebot business, driving market creation when the domestic voicebot sector was virtually non-existent. He has since served as subsidiary CEO and Executive Officer overseeing product businesses.
Recruitment drive
To accelerate model development, productisation, go-to-market, and global expansion, Kotoba Technologies is strengthening hiring across the board. The company is looking for teammates eager to break language barriers with world-class technology.
Open roles: Machine Learning Engineer, Full-Stack Engineer, Product Manager, Business Development & Global Sales, and more
Careers page: https://toothsome-bench-e67.notion.site/Kotoba-a29c10efa19543c880bd2206f08edeb8
Investor comments
Hidekazu “Emre” Yuasa (Partner, Globis Capital Partners)
“We’re delighted to invest in Kotoba Technologies. The company is developing extremely sophisticated speech-to-speech foundation models, and we expect this technology to remove language barriers across diverse applications. Starting in Japan—where language friction is especially high among advanced economies—Kotoba will expand to Asia and the world. We’re fully behind them!”
Takao Ozawa (CEO) & Shinichiro Hori (Director/Partner), Boost Capital
“Let’s boost together!”
Justin Turkat (Founder & Managing Partner, SIP Capital)
“Kotoba Technologies is trailblazing the future of Voice AI, right here in Japan! We are thrilled to continue our support for Nori, Jungo and the whole team since our founding investment in 2023.”
Joi Ito (Co-founder & Director, Digital Garage; President, Chiba Institute of Technology; former Director, MIT Media Lab)
“I’m thrilled to see two exceptional PhDs from top U.S. universities building cutting-edge real-time speech-AI solutions right here in Japan. I’m excited to support Kotoba Technologies on their journey toward global impact.”
Thomas Wolf (Co-founder & CSO, Hugging Face)
“Very excited about the extremely fast, simultaneous speech translation that Kotoba is building. Generative AI has the potential to break huge language barriers in Japan and Asia, bringing communities together and catalysing development.”
Toru Shimada (Angel Investor; founding member of Intelligence [now PERSOL CAREER], former EVP Rakuten Inc. and former President, Rakuten Baseball Club)
“Kotoba Technologies’ quest for real-time speech technology powered by generative AI has the potential to transcend language barriers and create tremendous social impact. I’m convinced that the passion and drive of these two founders—both PhDs from leading U.S. universities—will generate groundbreaking value from Japan to the world.”
Luke Zettlemoyer (Professor, University of Washington; Research Manager, Meta Platforms)
“Kotoba’s end-to-end speech model is an exciting and innovative approach to building the future of simultaneous machine translation. I’m thrilled to support their mission!”
Noah Smith (Professor, University of Washington; Senior Director of NLP Research, Allen Institute for AI)
“Real-time simultaneous translation was once an inspirational dream for AI scientists, and now Kotoba is making it a reality. I’m excited to see the impact of this work!”
About Kotoba Technologies
Founded in October 2023 by Dr Hiroyuki “Nori” Kojima (CEO) and Dr Jungo Kasai (CTO). At NVIDIA AI Summit Japan 2024, Kotoba delivered real-time captions for the keynote dialogue between Masayoshi Son and Jensen Huang before thousands of attendees. The company has been selected twice (Phase 1.5 and Phase 2) for Japan’s METI/NEDO GENIAC generative-AI programme.
Founders
Hiroyuki “Nori” Kojima, Ph.D. – CEO
Co-founded Kotoba Technologies in July 2023. Co-initiated the “Fugaku-LLM” project, which leverages the world-fastest supercomputer “Fugaku” for Japanese-language LLMs. Ph.D. in Computer Science from Cornell University. Winner of Best Paper at EMNLP 2022. Masason Foundation Scholar. Formerly at Facebook and Hugging Face.
Jungo Kasai, Ph.D. – CTO
Co-founded Kotoba Technologies in July 2023. Research Assistant Professor at Toyota Technological Institute at Chicago. Ph.D. in Computer Science from the University of Washington. Numerous publications at top conferences; Best Paper at NAACL 2022. Experience at Facebook, Microsoft, IBM, and AI2. IBM PhD Fellow, Masason Foundation Scholar, Funai Foundation Scholar.
Company name: Kotoba Technologies, Inc. / Kotoba Technologies Japan K.K.
Representative: Co-founder & CEO Hiroyuki Kojima
Locations: Seattle, Washington, USA / Otemachi Building 6F, 1-6-1 Otemachi, Chiyoda-ku, Tokyo
Business: Development of speech-AI foundation models and their real-world deployment
Official X (Twitter): https://x.com/kotoba_tech
Website: https://kotoba.tech