Played that track in the old "Le Mans 24 Hours" PS2 game. That double right hander was a nightmare in that game and I suppose it must be the same in reality. It's clearly a "shortcut" and completely destroys any sense of flow in this short version of Suzuka.
The suzuka west circuit completely bypasses the pitlane the F1 teams use. Hence, the additional pitlane located between spoon and 130r. A lot of tracks have similar setups. Bahrain for example, has another pitlane for use in different configurations too.
Just took this out from Google Earth and you can clearly see the building is along a pitlane, so that's where the boxes are. Of course it's a pit complex much too small for F1 standards but F1 never uses it anyway.
Looking at this picture you can also see very clearly a car park and a Kart track (suzukalike shaped) behind said buildinbg. More interesting, if you look up in the Casio direction you will see a small oval track. Suzuka Mini Superspeedway ??