Way of the Ninja (Veteran) is the first stage in Ninja Awakens!.
One thing about this stage overall is that you’re definitely going to want to bring anti-Floating Cats like Angry Delinquent Cat, Sadako Cat, Cameraman Cat or Necro-Dancer Cat. Take advantage of the fact that Flying Ninja Cat is a Floating enemy. Additionally, meatshields are a must.
If you have Sadako Cat, this stage is ridiculously easy. Just bring Sadako Cat, Necromancer Cat, and any cheap damage dealer, such as Dragon Cat. All you have to do is spam Kotatsu and Necromancer. The boss cannot advance, as it will be frozen and weakened. Dragon Cat is just there to make this fight a bit faster.