The Siam restaurant has a Japanese restaurant on the ground floor and Thai on the 1st floor. I have been to both several times, and definitely rate the Thai restaurant as one of the best I have been to in the North West. Slightly above average prices compared with other Thai restaurants in the area, but worth it. The Japanese area has several Teppan Yaki tables, where chefs cook in front of you. If you know your Japanese food (and I do, I studied and travelled in Japan), then be prepared, the chefs are not Japanese, and the tricks a bit lame at times. Its good fun with a group, but if you want real Japanese food there are better places to go in Manchester for example. I'd go for the Thai every time myself.
Siam Thai and Teppanyaki – Chester