Mashiro for Firefox is a subscription-based extension that enhances the experience of browsing Pixiv by allowing users to sort illustrations and manga by popularity. Originally developed as a Chrome extension, it has been adapted to run on Firefox, providing a seamless integration for users of this browser. The tool is designed for internet and network enthusiasts, specifically within the search and lookup tools category.

To use Mashiro, users need to install the extension and enable it from the extension menu while on Pixiv.com. Once activated, it allows users to sort search results by 'Illustrations' and filter them based on popularity. However, users should note that Mashiro is experimental and may not always function perfectly, as it relies on the popularity metrics of illustrations to deliver results.