As far as I know, there are no patterns out there that are specifically "bleach" shinigami wear, as their garment isn't exactly period accurate - it's animated.
So you'll have to find a normal kimono pattern, which is a good place to start, and then modify it to how you want it to be. Narrower sleeves? Don't make them as long. Bell-like sleeves? Draw a line from the bottom of the fabric under the wrist and up toward the body, then sew on that (to make the wrist opening bigger than the part around your bicep).
There are many kimono and robe patterns online and mentioned in the forums. Try searching google for "kimono pattern" and see what comes up.
The page I think you're reading about is www.sengokudaimyo.com
- he's a reenactor of ancient Japan and has done a ton of research. He used to have some tutorials up, but he's been revamping his page for years, so I don't know if anything has changed.