Kotoba Technologies' proprietary speech foundation model Koto has been selected to power Japanese-language conversations in Agentforce Voice, the voice capability of Salesforce's autonomous AI agent platform, Agentforce, provided in Japan by Salesforce Japan Co., Ltd. Agentforce Voice became available in Japan on August 7, 2026.

Agentforce Voice is a native voice layer that transforms conventional IVR (interactive voice response) systems, enabling AI agents to handle customer interactions autonomously over the phone. It can also be embedded into digital channels such as websites and mobile applications. With Koto now serving as the foundation for its Japanese-language conversations, Agentforce Voice delivers fluid, high-quality dialogue that handles honorific speech and the idioms of everyday spoken Japanese.

The phone: the most familiar channel, and the hardest one

The phone remains the primary point of contact between companies and their customers — for many organizations, the majority of inquiries still begin with a call. Yet long hold times and rigid automated menus consistently undermine the customer experience, and in Japan the shortage of contact center staff has become acute. Automating voice interactions with AI, without sacrificing quality, has moved from a nice-to-have to a business priority.

Japanese, however, is not an easy language for voice AI. Honorific registers, the idioms particular to spoken conversation, meaning that shifts with context — miss any of these and the customer immediately hears a machine. Delivering conversations that hold up in a business setting requires ultra-low-latency, high-accuracy speech recognition (STT) and speech synthesis (TTS), built on a speech foundation model that captures how Japanese actually works.

About Koto

Koto is an end-to-end speech AI model developed in-house at Kotoba for ultra-low-latency, real-time voice processing. In addition to speech recognition and synthesis for AI agents and voice interfaces, it supports speech-to-speech translation for simultaneous interpretation, and performs strongly across East Asian languages — particularly Japanese, Korean, and Chinese. Koto also runs on-premises and on-device, allowing it to meet the varied operational and security requirements of enterprise deployments.

Through this selection, Koto's Japanese speech recognition and synthesis technology is embedded in Agentforce Voice, supporting natural Japanese-language conversation over the phone channel. Kotoba is also a portfolio company of Salesforce Ventures, and the two companies continue to deepen their relationship on both the investment and business fronts.

Comments

Noriyuki Kojima, CEO and Co-founder, Kotoba Technologies

"Japanese demands a great deal of a voice AI system — honorific speech, the expressions particular to spoken language, nuance that depends on context. Koto was developed to handle exactly these characteristics and to deliver natural conversation at low latency. Having our technology selected for Agentforce Voice, from a global leader like Salesforce, tells us that the East Asian language speech AI we have been building has reached a standard that holds up in real enterprise operations. Together with Salesforce, we will do everything we can to help Japanese companies deliver more natural and more dependable customer experiences through Japanese-language support in Agentforce Voice."

Atsushi Mito, Senior Vice President, Product Specialization, Salesforce Japan Co., Ltd.

"In Japan, where the shortage of contact center staff continues to intensify, Agentforce Voice delivers a more seamless customer experience by allowing AI agents to handle phone interactions. To achieve natural, high-quality voice conversation in Japanese, we have adopted Kotoba Technologies' speech foundation model, Koto. Salesforce will continue working with Kotoba Technologies to help customers in Japan create new customer experiences built on collaboration between people and AI agents."

Looking ahead

Kotoba is pursuing a future in which language is no longer a border, advancing both the research behind the Koto speech foundation model and its deployment in the real world. Beginning with this collaboration with Salesforce, we will further expand our multilingual voice AI offerings — in Japanese, Korean, Chinese, and beyond — across contact centers, AI agents, and the broader enterprise landscape.

To discuss deploying or integrating Koto, please get in touch through kotoba_product@kotoba.tech