If you don't pay attention, you just might miss it! Soga is located on the second floor of the building, and they have a pretty small doorway on State Street, so look out.
Soga is definitely one of the places that has more authentic Chinese food, especially if you order off the Chinese menu. I've been here numerous times, and it seems like the food is on a bit of a decline. I think they switched owners recently, and now the food is SUPER salty. I normally order the garlic eggplant, and that's usually pretty good, despite the change in management.
I've also come here for hot pot, which is pretty fun. I was with a group of friends and we just ordered their "hot pot platters" with meat and veggies and two soup bases (spicy and not spicy). It's a nice environment for hanging out and having hot pot, and a pretty good deal.