After you defeat Poanna’s sister, there’s a side quest mission where you’re able to challenge the green dragon you’ve met before at the top hill North of The Seals. This guide will help you how to defeat him.
Guide to Beat The Dragon
The Last “Bikini Armour”
It’s impossible to defeat the dragon if you challenge him in a fair fight.
To beat Mr. Buff (the dragon), you need to unlock the nude mode (Unequipped).
To unlock Unequipped, first, you need to raise all your bikinis (except for Amazing Bikini) to 5000BP and at level 4 exposing resistance. After that, sleep in the inn using Nightmare Bikini. Pienetta will wake up at night. Go out and change your bikini to Unequipped. Now Pienetta is able to wandering at night while naked.
Challenge Mr. Buff and lose once. This will give Pienetta an idea how to defeat the dragon. Change your bikini to Unequipped and challenge Mr. Buff again. Now you are able to defeat him easily.
After you beat the dragon, you are now allowed to enter the tent in Reacon one that you were not allowed to access before.