How do you get to the hexagon in Dragon Quest IX?

Answer 1

When you enter the hexigon , there will be a large hexagon shaped room , take th e first left out of that room , continue then you will see a statue, move your character to the back of the statue and interact with it . then the first door should open! hope i helped!

Answer 2

First you follow the trail like you're going to the Starlight Express from Angel Falls.

While you are going down the trail, you'll see you will be able to go down into the forest. Go down and you will find a trail going to The Hexagon, where you'll find the Hexagoon, your first boss.