I think gai is ninja K because his Occupation is a ninja and and he also as the same ability as well /weapons

(1).His main ability is creating four until eight clones of himself like ninja K 

(2).he can sometimes teleport from one place to another Like ninja K

(3).he also has throwing stars like ninja K

and he also where's a hoodie and ninja K has a similar hoodie ,he also has the same gloves as gai ,as well he as the same interest to miyo as well