Ninja Kamui offense.

Best case scenario for the build is Arthur support.

Lv 10 Prince -> Ninja is 12 Str, 14 w/tonic, 16 w/ E rank, 20 w/ Arthur. This ORKOs every generic in C8 except the HP +5 Fighters near Flora. Combine that with 1x and you should have D rank for C9. C support + D rank is another +3 atk so 23. Level 12 makes that 24. This also ORKOs every generic on the map except the Guard stance Samurai but who cares about them. You reliably hit 18 AS for the guard stance lancers as well, packing 19 AS which also gets the unpaired Samurai though they don't matter.

Same song and dance in Birthright and Rinka exists.

In IK Kamui can leave C7 at like level 13-14 if you get all the treasure and Gunther exists. Don't feel like calculating.