Mugenfrontier

Dungeon 1

Pretty straight forward, just keep going up. You can smash rocks by pressing A. If you find a locked door, check the paths on the sides, one of them will have a computer you can operate to open the door.

Eventually, you'll get Kaguya (girl with sword) and you'll come to a door you can't open. Ignore it, and search the paths on the sides for a room with a red robot inside, which will be your first battle. After you're done, you'll exit the dungeon automatically and end up at the ship/base.

Ship

Rest and save here, when you're ready, head out to the world map.

World Map

Keep walking to the north and to the east, eventually you'll see the dungeon, it looks like a space ship on the outside.

Dungeon 2

Here you can climb stairs by holding the A button and moving with the pad, if you let go of the A button you'll fall instantly. Your goal is to reach the top to turn on the elevator you saw at the bottom level. Once you do so, keep walking to the right into what looks like an abandoned lab. Eventually you'll met T-elos, follow her to a room with a lonely console, turn it on and you'll have another boss fight (3 Golem Gnosis). Once you're done with the boss, head out (use the elevator) and back into the world map.

World Map

Head to the north and west of the dungeon and you'll see a vortex, come near it and check it with the A button to go through it. You'll end up in a different map, which looks very japanese. In this new map, walk to the east until you see a town, enter it.

Japanese Town

When you get here, there will be some dialog and you'll lose Kaguya temporarily from your party. Besides your normal options (Rest, Save, Shop, etc.) there's another option that lets you visit an area within the town, some sort of temple thing, go there and head north until you see Kaguya, more dialog occurs and you get Kaguya back. Rest, shop and save if you want and head out.

World Map

Head North and East, you'll eventually see the dungeon (looks like a cave/rock castle on the outside).

Dungeon 3

In the first room there's a save point and a statue that fully recovers your HP/SP, heal and save if you want, then walk all the way north and then right, you'll see a door in the wall leading up and a path to the right, take the door, you'll come out in a room with many crystal (which you can't break at this point), walk left and make it to the bottom level, then look for a path on the left. An event will occur here and you'll get Suzuka. Head back a to the previous room and walk north (or go back to the beginning and save/heal first, since the next boss is hard), you'll see a catgirl and another event will trigger, leading to a boss fight.