We don't know the true reason behind the split-toe design of Tabi shoes worn by Ninjas but according to Topo Athletics it offers "more security and a stronger connection to your footwear".
It makes you feel as if the shoes are part of your feet - useful when you're a Ninja jumping from tree to tree or from rooftop to rooftop.
Topo is not the first to adapt the design to modern shoes but they're interesting nonetheless. They have an anatomically designed toe box to allow the remaining toes to spread naturally for comfort and welded seams to prevent chafing.
The shoes may appeal to barefoot runners because it is zero drop i.e. they have a neutral height from heel to toe so your feet are parallel to the ground when you're standing still (as if you're barefoot).
One of the three models to be launched comes with BOA lacing system - a high tech lacing system that allows you to rotate a dial to tighten the laces. Coming Summer 2013.
Topo tabi shoes have been discontinued by the company. It may help with balance but it's probably not that great overall.