Jigen ryu? does it realy only take one strike?

i have a friend claiming he is a master of jigen ryu and that it only takes one strike to finish a fight im skeptical and yet he is so cocky and is like "you beter be glad i cant fight you" yet im thinking what is the point of 1 strike if you cant hit ur opponent im not spouting off im just curious why is he so sure he could kill me in one movement yet i have no trouble dodging eskrima sticks in the ring (i take combined arts and karate yet i love escrima sticks and enjoy dodging i hardly ever block mostly i just dodge but how efective is jigen ryu?