AI phone agents in Japanese

ThunderPhone supports Japanese across the product: agents can speak and understand Japanese on calls, the dashboard ships a Japanese interface, and the docs site has a dedicated Japanese edition.

Japanese is one of ThunderPhone's 47 supported voice languages. It is an included language, so choosing Japanese does not add a language surcharge to the selected Spark (2¢/min), Bolt (5¢/min), or Storm (9¢/min) engine rate. Pricing is pay as you go, with no subscription.

Japanese voice availability and pricing

The current catalog includes eight voices that support Japanese:

• six multilingual voices on the included Japanese language path; and
• two premium Japanese voices, Yumiko and Ren.

The premium voices add 3¢ per minute to the engine rate; the other compatible voices carry no language charge. All figures are before telephony and other optional charges, and the builder shows the current all-in rate as settings change.

The voice picker filters the catalog to voices that support every language selected for the agent, and each voice can be previewed before deployment. Japanese phone conversations carry strong register expectations, so evaluate candidates against real calls: honorific and polite forms, personal and company names, addresses, numbers read aloud, and katakana loanwords your callers actually use.

Japanese in the dashboard and documentation

Japanese is a shipped dashboard locale, not just a call setting. A team can configure prompts, review calls and transcripts, and manage the organization entirely in the Japanese interface.

ThunderPhone publishes a dedicated Japanese documentation edition on its docs site, giving Japanese-speaking builders localized product guidance in addition to a Japanese-speaking agent experience.

Japanese and English in one call

An agent has one primary language and can have additional languages. If Japanese is primary and English is additional—or the reverse—the agent switches automatically when the caller changes language, within the same call. No phone-tree option or separate number is required.

The selected voice must support all configured languages. Test realistic switch points rather than assuming every transition will behave the same way—for example, a caller who conducts the call in Japanese but spells out an email address, gives a Western name, or asks a question in English.

Sample Japanese call experience

The following flow is written in English to describe the caller experience.

Agent starts in Japanese: Greets the caller politely, identifies the business, and asks how it can help.

Caller answers in Japanese: Says they want to change tomorrow's reservation.

Agent continues in Japanese: Confirms the caller's name, looks up the approved scheduling action, and offers two available times.

Caller switches to English: “Actually, could we make it Friday evening?”

Agent switches to English: Offers the available Friday-evening time and asks for confirmation.

Caller returns to Japanese: Confirms the new reservation.

Agent returns to Japanese: Repeats the final date and time in polite form, then closes the call according to the business's instructions.

Build and test a Japanese agent

1. Set Japanese as the primary language, or add it to an agent's additional languages.
2. Choose one of the eight compatible voices that supports the complete selected language set.
3. Write the operating prompt in the language your team can review most reliably; the agent's spoken language is configured separately.
4. Attach only approved knowledge sources and integrations, with reviewed Japanese wording where exact phrasing and politeness level matter.
5. Run Japanese-only, English-only, and mixed-language simulations.
6. Review pronunciation, register, transcripts, tool actions, transfers, and escalation behavior before deployment.

Frequently asked questions

Does ThunderPhone support Japanese voice calls?

Yes. Japanese is one of ThunderPhone's 47 supported voice languages and currently has eight compatible voices in the catalog.

Does Japanese cost extra as a language?

No. Japanese is an included language, so it adds no language surcharge to the Spark, Bolt, or Storm engine rate. Pricing is pay as you go with no subscription.

Are premium Japanese voices available?

Yes. The catalog lists two premium Japanese voices, Yumiko and Ren, at an optional 3¢ per minute on top of the engine rate.

Is the dashboard available in Japanese?

Yes. Japanese is a shipped dashboard locale, so builders can operate the product in Japanese.

Are the ThunderPhone docs available in Japanese?

Yes. ThunderPhone publishes a dedicated Japanese documentation edition on its docs site.

Can a Japanese agent switch to English during a call?

Yes. Add English as an additional language and select a voice that supports both. The agent can switch automatically when the caller changes language mid-call.