Generally their jeans are pretty TTS. I went for 32 in my 400T, and the waist measured about 31.5" when new/one-wash. From the looks of it, their WW2 jeans are cut pretty generously.
I don't own any jackets from them, but the flannel and traveling shirt, both size 3, are pretty roomy as well compared to most other Japanese size L pieces I have from other brands.