"Defeat absolutely every foe in the Otherworld in one go."
This means finding every bounty from the first continent, including the secret bounty, then beating all of them in the otherworld in one go. There are wanted posters in the guild showing which bounties are still missing.
Dungeons have 10 different arrangements for each floor, chosen randomly. 5 of those floors include a bounty. Goral can choose a specific floor ID for you, which will be set as the first floor when entering a dungeon. You can hunt the bounties by systematically browsing through every single floor ID, running through dungeons until you have found every bounty (depends on luck, mine is atrocious) or by consulting a guide. Goral actually tells you to just use a guide to save you the trouble.

The guide I found is in Japanese, so I decided to translate it here.
The list of bounties is gathered from posts made by anonymous users who discovered them and shared the IDs on HaD's Seesaawiki page. They might not be 100% accurate, but the ones I was missing were all correct.












Secret bounty is located on floor ID 9 of the Dark Lord's Castle.

Upgrade Village/Town to level 100.

I believe the quickest way to hit 100 on village is to grind in the otherworld, either the one in the village or on the second continent. Get in, beat some of the toughest foes, get out and repeat. To upgrade the village just spend all the points you gathered. The otherworld is also a great place to level a character to 999, just give her the 5x accessory.

For upgrading the town to 100 you're going to need gold. Lots and lots of gold. A great way to do this is:
-equip a character with an expensive ring (obtained from the first dungeon, doubles gold from battles)
-get Lara, Moski and Robotta in your party (might not be the best choice, but definitely good enough)
-make sure you have over 999 AGI on every character
-farm in the goblin mines until you turn into a goblin.

Seesaawiki page suggests you to increase the amount of enemies every run and clear the entire dungeon every time you enter, but I did this slightly differently. I would not recommend fighting regular mobs since they're not worth a lot, and because you might want to fight as little as possible since the English release suffers from crashes. SAVE OFTEN if you've experienced these crashes. Hunt down the elite mobs (the ones with a cape) for 166k gold each battle, then homeward out when you've cleared floor 4.

The party I suggested is for the rare mobs. Always engage them from behind for the preemptive attack, as they tend to run away if they get a turn. You're looking for giant golden slimes, which are worth a million each with the expensive ring. If you get silvers just escape, as you might sometimes get a new roll when doing this.
When you hit gold, have Lara and Robotta use their machineguns, Moski her Slurp All and Ralph a random AOE. I also suggest saving after defeating giant gold slimes.

Invest the gold in spells and sell them back for extra EXP