You eventually unlock the option to play as any character you can knock out (pressing select switches your weapon from blade to blunt side). The easiest way to do that is unlock hard by playing a few times, then select hard mode, beat up the two thugs harassing the girl in the village, eat a turnip, and leave. It ranks you as vegetarian and gives you 1050 points. You unlock everything relating to samurai points at 10,000. That includes all the costumes, head, extra options (blood color, etc.) and a lot of accessories.
Basically, any NPC you knock out is later added to the list (there are 100+) to use. You can customize them by adding various accessories (hats, glasses, devil wings, etc.) and select their animation style. If you pick the little girl, for example, her default animation set has her moving really slow because of her skirt.
The only NPC you can't use are little kids and dogs.
surprisingly, the best npc isn't the young girl. In one part of the game you
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get attacked by one of the characters from Shinobido. I knocked him out and play as a ninja. Right now I'm actually trying to find him again so I can kill him and take his sword.
Ni to ryu is the two-sword style.
I haven't even beaten this once yet, LOL. I'm finding it kind of boring now, TBH. Wandering aimlessly isn't that fun.
I felt the same until it kinda clicked and I began to understand it. When I learned all the icons, the time and that I could quick move to location, it became all good. I don't really wander unless I'm actually looking for random npcs to show up (Samurai Hunter, who has two ninja blades). I'm played through many times and only got 5 endings (don't know how many total, but a trophy says there are more).
and yeah, the dual sword stuff is crazy strong. In terms of sheer power, it can just shred strong enemies in a few hits.
For as much as I have played already, I haven't even done the sword creating yet. I have really good parts that I don't want to waste on a style that I don't have all the skills for yet.