The way to see what kind of the sauce is used in the shops is chiefly to check the noren (a short -split- curtain hung at the entrance of a room) put at the entrance of the shops because these sauce companies make the noren with their name printed on it and provide the shops which buy the sauce with it.
その見分け方は、これらソース会社が自社のネームが入った暖簾を作り、納入先のお店に提供しているため、お店入口に掛けてある暖簾を見れば使っているソースがたいてい分かる。