Must be nice to live in a place where your police are so bored, having such low crime rates in a homogeneous, high-trust society, that they have to do petty stuff like this to earn their paycheck.
"If the Yakuza are criminals, why don't the Japanese police simply arrest them?"
https://www.quora.com/If-the-Yakuza-are-criminals-why-dont-t...
See; While many Yakuza syndicates, notably the Yamaguchi-gumi, officially forbid their members from engaging in drug trafficking, some other Yakuza syndicates, notably the Dojin-kai, are heavily involved in it.