I don't think you have bought a Yanagisawa stencils (which were always, I think, bearing the made in Japan denomination and often some signs related to the Yanagisawa factory). I think the S on the neck was meant to deceive and in the best of cases to relate to the brand Solotone but was an obvious innuendo to Selmer. I have seen Solotone Artists before and inspite of the fact that some people want them to be something better they hardly ever are and certainly have nothing to do with Selmer.
Anyway I have seen some solotones before but they were different from this one. If you cannot find a Made in Italy anywhere and there is no serial number then I think that you might have bought (and that would be consistent with the pearls be made of transparent plastic that I have only ever seen on East German d early Taiwanese or Chinese horns) a Taiwanese ( the other brand using a black pearl on the G# was obviously KHS otherwise known as Jupiter) or Chinese horn.