Hey.
Yes, a few Law schools provide course only in Business Law.
First of all, if you're interested in Law overall you cab pursue a 3 year Law course too after your Bcom and after that you can specialise in Business law.
But if you're interested in only Business Law then there are courses like MA in Business law, MBL- Masters in Business Laws which can be pursued by any one who has completed an undergraduate degree. Colleges like NLSIU Bangalore, NUJS, Kolkata, Jindal Global Law School etc offer this course.
Best of luck