Kousuke did as he promised to in handling Nishikawa Takiji's case. Using his power and influence, he provided concrete evidence after handing the man to the police.
When the police were skeptical of how beaten up Nishikawa Takiji was, Kousuke calmly stated that the man was involved in a brawl with a gang for fighting over women.
The real love drug was found in his possession, after being planted by one of Kousuke's men. The two women just acted drunk after consuming the fake drugs Nishikawa Takiji bought from Kurasu.
And...
The recording Nishikawa Takiji did for his own pleasure became a double-edged sword for him.
Aside from the evidence of Nishikawa Takiji preying on minors and doing drugs, Kousuke also brought up the cases of him trying to forge his elder brother's signature and stamp seal again.
The list of his crimes kept getting longer once his residence got ransacked by the police.
