Kai’s test 

Kai: what are you guys doing here? Michael: it’s time for your test you will be going up against your brother to use the strongest.Nami: what is this Kai.Kai: cause I’m a demon goddess hybrid every eight years I will have to go against my brother to see who holds the title as the strongest son.Robin: I remember reading about this ones  it’s just like when we were in the hot spring and so if I put my finger in one of the holes in your back, your legs go paralyzed for about two hours.