You can use the Folkwear pattern for haori and modify the sleeves and make the whole coat longer.
Or use Simplicity 5839 haori and do the same thing. (That pattern has a haori and a kimono pattern in it.)
Then decide if you want a slit at the back or the coat or not. Depends on the character and manga/anime look, or if your character has a sword through the obi like normal. If so, the slit is a reallly good idea...
Also, change the lining so it runs all the way to bottom. The patterns usually have the lining start halfway up the coat like a real haori normally would, but that's not Bleach style.
The key is to not use a kimono pattern, you need to start with a haori pattern.
This is because the captain's coats don't fold over, they come straight down at the front.
For the lab coats? I'd have to look at pics of those first to add my two cents to the advice here on that.... happy sewing!