Ben Hinshelwood, Gavin Kerr, Jason White, Rob Russell, Stuart Grimes and Gordon Ross are the returning players, who were not available for selection last week.
They are replacing Stuart Moffat, Bruce Douglas, Scott Gray, Ross Ford, Alastair Kellock and Glasgow's Andy Craig.
Williams said "We have brought in some of the exile players for the match against Japan. There is an opportunity with this Test to broaden the squad and in doing so increase the competition for places.
"The emphasis on this squad is to deliver a performance and make sure the Scotland jersey is competitive and emphasize that no one has it by right. We are looking for a win against Japan but they are a side who are playing very well at the moment having recently beaten Russia and Canada," he added.
Scotland squad (sponsor The Famous Grouse) to play Japan in the Abbey Autumn Test at McDiarmid Park, Perth on Saturday 13 November, kick-off 5.30pm
Backs
Mike Blair (Edinburgh Rugby)
Chris Cusiter (The Borders)
Andrew Henderson (Glasgow Rugby)
Ben Hinshelwood (Worcester)
Sean Lamont (Glasgow Rugby)
Graeme Morrison (Glasgow Rugby)
Dan Parks (Glasgow Rugby)
Chris Paterson (Edinburgh Rugby)
Gordon Ross (Leeds Tykes)
Hugo Southwell (Edinburgh Rugby)
Forwards
Gordon Bulloch (Glasgow Rugby) CAPTAIN
Stuart Grimes (Newcastle Falcons)
Nathan Hines (Edinburgh Rugby)
Allister Hogg (Edinburgh Rugby)
Allan Jacobsen (Edinburgh Rugby)
Gavin Kerr (Leeds Tykes)
Donnie Macfadyen (Glasgow Rugby)
Scott MacLeod (The Borders)
Jon Petrie (Glasgow Rugby)
Robbie Russell (London Irish)
Craig Smith (Edinburgh Rugby)
Jason White (Sale Sharks)