Basically uhhh go onto amazon and spend $181 on a Murasama Replica.
Go to the supermarket, get a bunch of tinfoil and Plate your body with it, like armor.

Congratulations, You have Become Jetstream Sam, as long as you can swing that sword, it is that simple.

Before your path to fighting god you have to climb the World Marshall Building, kick the ♥♥♥♥ out of a Metal Gear, which should be relatively easy, and then armstrong, who if you beat, will subsiquently impale your arm to the floor.

fear not though, if he does, out of the kindness of his heart, he will give you a sick ass robot arm.

To beat armstrong, time your slices right to hit him in spots not protected by his nanomachines

This part is Essentially to the speedrun, but will be harder. If you don't care about speedrunning, take this part slow.

Basically, you will need to go to the nearest church and climb through the skylight. If its covered in stained glass you have to break through.
After you do that you should be in heaven, this is the hard part, Finding him, it will be difficult because as we all know, God is scared of Brazilians, because they can double Jump. He'll probably be hiding somewhere where you don't expect it.
Once you find him he'll engage in his mech suit, Take it down and beat him, and finally

You have become Jetstream Sam.

Uhhhh good job, now you can go settle down and have a wife and children, knowing that you're Jetstream Sam. Enjoy