Have a troubled past: It always helps to have a troubled past when you want to grow up to be a warrior. It builds character. Or, so, they say. It's okay if you didn't know this, and had a cushy childhood. Get into some neighbourhood brawls, anger a parent, and live for a few days in abject poverty (or, ask your parents to cut off your pocket money for a week).
Learn martial arts: It's important to know any kind of self-defence before you enter the realm of a big-league warrior. Kung-fu, karate, tai chi… Or, make up your own martial art. That way, you don't even have to go through the levels. You are the master, immediately. And, you can give it some cool name too.
Be an introvert: The key to being a hot-shot warrior is to have a non-existent social life. If you run away from women, and answer questions with gruff noises, rest assured you will be a symbol of mystic, animal power.
Inherit a Samurai sword: If your family doesn't have a Samurai sword, you can try sword collectors, dealers or hobbyists. If none of that works, buy a ‘make-it-yourself-Samurai-sword' kit, and starting doing it. You could always Google it for the design. But, don't use thermocol or sandpaper; it needs metal so it doesn't disintegrate when washed.
Challenge an existing warrior: This might be a tad tough as it isn't really 20th Century! You could challenge a kid loitering around with a plastic sword. I'm not sure that's warrior-like. But, works better than knocking every door asking for a challenger!
Keywords: Samurai warrior