Went here with a gluten intolerant friend because they put labels on all the buffet dishes saying what's in everything, including meat, fish, dairy, eggs, wheat, etc. There were a lot of gluten free dishes and a lot of vegetarian dishes - about 70% for both.
The second time I went, there were fewer choices. Lots of stuff with fish, lots of stuff with wheat, and seeing as the buffet price is set (around 2000 yen), it wasn't worth it and we went across the street to Brown Rice Cafe.
Cons: expensive-ish, hit and miss menu, serves meat