Here at Yaraku, we believe generative AI and LLMs can contribute significantly to productivity and efficiency. New models with better intelligence and more capabilities are being developed all the time. 

Although we recently updated the models, AI development is advancing at such a fast pace that new models are already offering significant improvements. To bring our users the best options, we are updating our GPT models as follows: 

　

Change date

May 20, 2026 (Wed),（JST）
There will be no downtime due to this update.

1. GPT 5.4-mini and GPT 5.4

Replacing our current default engine GPT 5-mini will be GPT 5.4-mini. Our GPT 5.1 will also be replaced with GPT 5.4

GPT 5.4 was released in March 2026. From OpenAI’s website:

“GPT‑5.4 brings together the best of our recent advances in reasoning, coding, and agentic workflows into a single frontier model.”

The GPT 5.4-mini model is a significant improvement over the current GPT 5-mini. It can even compete with the current GPT 5.1 despite being a “-mini” version. Users should also see less of the problems that the 5-mini model might have such as segments being untranslated.   

For those concerned about security, please rest assured. Our Business Associate Agreement still applies so the same security and data protections will continue to be available with the new model. 

References

Security of GPT-5.1 and GPT-5 mini

2. AI Dictionary Update

With this update to GPT 5.4, we are also taking the opportunity to update the AI Dictionary functionality.

Our AI Dictionary is one of our newer functions. By highlighting text in the Edit page, a popup will appear with AI-generated definitions, synonyms, and example sentences. This can be used as reference when making changes to the translation, or as assistance for choosing the best phrasing and wording, or as a lookup to check words you don’t know or languages that you can’t read . 

Previously the AI Dictionary used GPT-4.1 to generate the dictionary entry but with this update it will be powered by GPT-5.4. While the functionality and usage will be the same, the content will be more up-to-date and more accurate thanks to the more newer model. 

Enjoy the benefits of the upgraded Yaraku Translate!