This page explains how to solve the quest "Song Sung Long" in Yo-kai Watch.

Start the Quest

Go into Frostia's Place in Downtown Springdale at night. Talk to a man there to start the quest.

Get the singer to stop!

Talk to the guy who won't stop singing.

Stop the crooning Yo-kai!

Use the Lens to find a hidden Croonger nearby, then defeat it.

Report back!

Talk to the friend to complete the quest.