If you purchase a license for Paint Tool SAI 2 (costing roughly 5,000 JPY or ~$35 USD), you are legally permitted to install the software on your own machines. To make it portable, you can manually install SAI 2 to a folder on your USB drive instead of C:\Program Files . As long as you use your own legitimate license file ( saidll.dll or the license key), you are not violating the terms of use.
Why go through the effort of making SAI 2 portable? Because SAI 2 has specific advantages over cloud-based apps like Krita or Photoshop when used on the go: paint tool sai 2 portable
A version of SAI 2 is typically created by: If you purchase a license for Paint Tool
Open sai2.ini (in init folder) and change relative paths: Why go through the effort of making SAI 2 portable
that does not require a traditional installation process; it is a single standalone file you can run directly from a folder or USB drive. How "Portable" Functionality Works Because the developer, , releases the preview as a
system—a new gift in Version 2—had quietly saved her progress in the background. The Legacy of the Light