For anyone who's wondering why Yuu and this new guy haven't turned into chickens even though they're 18 and 19, it's because adulthood in Japan is recognized as 20 years old instead of 18 years.
Lemme guess, 19 years old there going to turn into a chicken next chapter then he would have a green light to kill him? Either that or Tora is going to turn into a chicken from all the pent up rage and bite weirdo in the head and then proceed to bit everyone's head off. ?