This page explains how to solve the quest "Detective Quest ①" in Yo-kai Watch.
Start the Quest
Talk to one of the three boys to the right of Springdale Elementary to start the quest.
Solve the riddle!
The hidden badge is in the crosswalk between the Lambert Post Office and the Piggleston Bank in Uptown Springdale. It's not marked on the map, so you will have to walk around the crosswalk until an exclamation mark appears above your head. Check that spot to find the badge.
Report to the detectives!
Go back and talk to the boy to complete the quest.
Return to the List of Quests.