Of course, what he gave you was really poison.
Brainwashed into using the poison, Imia’s Uncle was tasked with poisoning the well with his own hands.
It would be quite troublesome to make these arrangements, but it avoided suspicion.
To have planned that elaborately ahead, it must have been difficult.
Imia’s Uncle: “Then I was to put the entire village to sleep with sleeping pills, and during that time-”
Naofumi: “Wait…sleeping pills?”