Koroshiya wa Kyou mo BBA o Korosenai. - Vol. 1 Ch. 7 - Momiyama Takayuki

[MangaDex]

 

[HDMI1]

The vacuum truck mentioned is the type used to empty portable toilets and septic tanks, meaning it's full of shit.

Also:

 

[inversefate]

That was the opposite direction I thought it would go

 

[Xamdiz]

LMAO amazing plot twist