Wansu (any spelling is acceptable as there is no 'standaridzed' way to translate the Hogan into English, is the source form that Funakoshi Sensei helped transform into Empi.
There is a rough structural relationship from the Okinawan Wansu to the Japanese Empi.
The name was changed to be more socially acceptable to the Japanese (who were conquering China at that time).
In turn I know of a Penna. Shorin group that have a 'Super-empi', or jazzed up version of Empi. This is interesting as they took a form that came from Shorin background and was modified into the Shotokan versions, and then took it back in the process.
Also their choice of name is a play on Goju's Superimpe kata, too.
The Isshinryu Wansu, a derivative of Shimabuku Tatsuo's training with Kyan Sensei, actually has an additional ending tacked on to it revealing several other sources of material, such as the low side kicks as in Goju.
Often overlooked as a short kata, the Wansu techniques are very powerful in application.
Bushi No Te Isshinryu