I wouldn't be too focused on getting a particular steel, especially when it can be as rarely used (relatively) as L6. I don't know how much of a noob you are, but a lot of people who are looking for "tough" or "hard use" knives typically have some unrealistic idea of what a well made blade can do. This is often due to Hollywood where you see people cutting through chains, chopping down trees with one slash of a katana, or prying open steel doors. Even if you get some of the toughest blades around, you won't want to chop into hard materials like steel or concrete because no matter how good the steel is, it will mess up a perfectly good edge.
Steel/ blade technology is sufficiently advanced now that even if you don't have THE toughest blade around, you'll still be able to do all the stuff that is within reason for any blade. Because of this, other than making sure you're working with a reputable maker or company, you'll probably want to look at a design that appeals to you since if it's coming from a good maker or company, it'll do what it's supposed to do. If you're looking for a nice Japanese-style tanto fighting knife, you might be interested in CRKT's Hisshou or Shinbu:
If you really have to have a knife that you can do unreasonable things with, a company with a great reputation for that is the Busse family knives (Busse, Swamp Rat, Scrap Yard Knive). But because you're focused on the steel itself, you'll be limited to their designs, which last I check don't have many Japanese styled blades.