Jin Sakai build?

[Oni Shogun]

What class/feats would he possibly have? He seems like a mix of fighter and rogue somewhat? He started off a Samurai and then becomes more ninja like as the story progresses?

[Alkarius]

Fighter with Rogue Archetype is how I'd build him.
High STR and DEX, wielding all kinds of weapons like Katana, Kunai (flavor a Dart or Shuriken), Bow, and Bombs if you can find them. Will make runes pretty expensive but Jin used a lot of different weapons.
I'd stick with using the Katana with 1 hand and leaving the other hand free, so feats like Dual-Handed Assault and Quick Draw would be thematic.
Stealth, Acrobatics, and Athletics would be ideal.
Aside from that, whatever is clever.

[Oni Shogun]

Problem is you cannot do sneak attack damage with any martial weapon doing more than a d6, and that includes Dual Handed Assault.

Swashbucker could work well for Samurai/Ronin or even Ninja types who fight more flashy. Been thinking of a Hellborn Ronin Swashbuckler.

[gesalt]

Thief rogue. Best reserve it for an ABP game. Elven curve blade as your "close enough" katana, thrower's bandolier for your various thrown things and a bow. Gets you all your skills too.