There always seems to be something interesting happening on Friendship Island. Currently boulders have appeared in a few places in the Gemstone Mountain area.
You could try to remove them, but even your pickaxe is no match for these sizeable hunks of rock. You’re going to need to call in someone with supersonic powers.
Prerequisites For The ‘Heavy Metal Hoedown’ Quest

You won’t notice these large boulders in Hello Kitty Island Adventure until you’ve progressed to a certain point in the main story. Here’s what you need to do to get this quest:
Have access to Gemstone Mountain.
Have Pekkle at friendship level 10 or above.
Complete ‘Enraging Ruins‘ quest.
Complete ‘Fire Up The Volcano‘ quest.
To check on whether or not you have access to this quest, you can check your ‘Active Quests’ log in the main menu. You’ll find it under the ‘Friendship Quests‘ section.
Talk To Pekkle

To begin this quest, you’ll need to talk to Pekkle once you’ve met the prerequisites. You’ll find him just north of the Dance Hall near one of the mine entrances.
He’ll explain how the boulders showed up, and give you their locations. Before you worry about the locations, however, you’ll need to talk to Retsuko to see if you can borrow her sonically powerful vocal cords.
The quest icon to search for on the map is a microphone. Unless you have an in-progress quest, Retsuko should be at the Hot Springs. You can use the Hot Springs fast-travel waypoint to get there quickly if you have it unlocked.
Retsuko should have a blue exclamation point above her head. Retsuko’s still feeling a bit apprehensive about singing in front of others, but she’ll eventually agree to help.
She’ll automatically follow you at the conclusion of the dialogue. You’ll need to return to Pekkle.
First Boulder location north of the Dance Hall

You’ll need to chat with Pekkle once you have Retsuko following you. After Pekkle and Retsuko are introduced, Retsuko will automatically do her signature singing.
Pekkle will head to the second location and will wait for you there. The map icon will lead you near Pompompurin’s boat.
Second Boulder Location At Pompompurin’s Boat Dock

Meet Pekkle at the second boulder location for the ‘Heavy Metal Hoedown’. You can use the Oasis fast-travel waypoint to get there quickly if you have it unlocked.
Talk to Pekkle again once you arrive at the location. This boulder is even larger than the last, and Pekkle will need to help this time to turn this boulder to dust. Follow Pekkle to the third boulder location.
Third Boulder Location Near Dance Hall Entrance

The third boulder location is just north of the Gemstone Town fast-travel waypoint. Meet Pekkle and Retsuko there, talk to Pekkle to try and get rid of the boulder.
If you’re thinking this is going to be the biggest boulder of all, you’d be right. All three of you are going to have to help to clear out the very last boulder.
Once you finish the dialogue the quest will complete.
