Clannad will be released for the Nintendo Switch via the Nintendo eShop in the west on July 4, following the announcement made by Prototype themselves.
Similiar to the Japanese version, the western version will support in-game language switching between English and Japanese text. Physical copies of the game can only be obtained in Japan, if physical copies are your cup of tea.
Clannad made its debut for the PC back in 2004, and has since made its way to other platforms, including the PlayStation 2, PSP, Xbox 360, PlayStation 3, Android, PS Vita and the PlayStation 4. the Switch and the Playstation 4 version share the same traits, as they are both available digitally in the west, physically in Japan.
You can have a read on the game’s details here, on the official Nintendo eShop page.