Using the Japanese's plan, on the surface, there were only Zhao Zhonglin as the mastermind and Xie Lang as the executor. Secretly, who knows how many people were providing support, whether openly or covertly.
If they retaliated against Xie Lang shortly after Zhao Zhonglin's funeral service, it would alarm those who were supporting from the shadows. That group of people was like a barrel of explosives, ready to detonate at the slightest touch. Killing Xie Lang might drive them to act in desperation.
Therefore, the task of killing Xie Lang was outsourced to the Azure Dragon Association, and it was done in such a roundabout way, to avoid implicating themselves.
"Since they're afraid of getting involved, why are they so eager for Xie Lang's head? And hiring an assassin from the Azure Dragon Association shifts the blame onto them. Afterwards, they plan to use the Association to appease the anxious parties. Do they think I'm stupid?"