Based on its level, how slow katanas are in the premature lvls, majority of the mobs weak to piercing in the lower lvls, and the terrible DMG katanas you can only obtain in those lvls, this is the best weapon for any NIN till lvl 40 and going into Elemental Wheel spamming phase.
Stock up on Racc/Rattk/Rice Dumplings and spam these suckers for a lot of damage. Too bad the cost and inventory space adds up and ppl don't know much about shurikens.