To make sure you don't get lost in the earlier dungeons, let's do a recap on it ;)
A bit of exploring around the island and dungeons. The following days will be about the first three dungeons you'll encounter on your adventure.
The first one is the Digitoll Cavel. This is where you'll begin your adventure and where you hope to find your "special someone". But it turns out your not strong enough yet, so it's back to the main island to explore the other dungeons first.
The monsters in the Digitoll Cavel are vulnerable to fire types and especially to the antenna skill "Fireball". Watch out for your ice Denpa Men as they are not so well equipped in this dungeon.
Did you have trouble getting through this first dungeon?
The Digitoll Cavel is freely playable in the free demo version of the Denpa Men on the Nintendo eShop.
EDIT: As some of you mentioned this is not the Tower of Evil, but the entrance to the lower parts of the tower, the Digitoll Cave. I edited the post but a thank you to Jamie, Bippy, Kari and Brian for noticing.