I'm not sure if I should be surprised at the length some folks' obsessively dig into Sugaya's alleged partner (talking about Japanese ones in this case, as foreign fans don't have access due to the language barrier).
Thought it was just a random stab in the dark thingy on fan sites/blogs, but if Oricon News posts an article with the name of the supposedly commoner, is it supposed to be legit now?
http://www.oricon.co.jp/article/321076/To be fair, that one is from Nikkan Sports and Oricon just reposts ala google/yahoo fashion. No idea what and why some random idol news is from sports site and who knows where that came from. The line between legit news and gossip (fake news!) blurs increasingly and Japan is of course no exception. But man, if one ever posts anything public on twitter or any platform ever, it's Liam Neeson Taken all over him/her.