C1400 Sparring
Yagyuu Kenjirou was a Supreme Expert, so he might not be able to do anything to him and Zhou Liren, but if he ambushed other people, even with the protection of someone with First Army, he would definitely be in danger. According to the rules of sneak attacks, a Ninja would be even harder to guard against than normal Fighter, not to mention a Ninja with the strength of a Supreme Expert