Japanized for Twenty Twenty-One is a free WordPress plugin designed to customize the Twenty Twenty-One theme specifically for Japanese users. It offers a range of features including the ability to set the font family to Noto Sans JP and adjust font sizes, catering to the specific typographic needs of the Japanese language. Additionally, users can add major social media icons popular in Japan, modify footer text, and set content width.

This plugin also enhances usability by incorporating features like a breadcrumb navigation system, a table of contents that can automatically insert into a sticky sidebar, and a Scroll Back to Top button for easier navigation. Users can personalize their website further by setting a background image for the header. It is important to note that some features may not function in Internet Explorer.