Original sentence: In this way, Kishi maintained that once the Japanese proved that they were the ones with the power, the dog-like Chinese would come to be naturally obedient to their Japanese masters, and as such the Japanese had to behave with a great deal of sternness to prove that they were the masters
Edited sentence: In this way, Kishi maintained that once the Japanese proved that they were the ones with the power, the supposedly dog-like Chinese would come to be naturally obedient to their Japanese masters, and as such the Japanese had to behave with a great deal of sternness to prove that they were the masters