I really don't it like when manga brush off literal felonies or serious crimes in general. Like this kind of shit, depicted in this manga, regardless of the fact that she let him go, could land you 20 years in a federal prison in the States. IDK about Japan, but considering they're generally harsher in punishments, I can't imagine it's all that different.
What was depicted here, drugging and tying someone up, is literally second degree kidnapping, assault, battery, and false imprisonment / unlawful detention and probably a list of other crimes. This is some serious fucking shit, and it's just puffed away like it's no big deal because mild comedy manga.