"The devil's banquet"
Notes: Reward in money will depend on how many enemies you kill, except when the mission is to kill all the enemies.
Let's move to Town of Spitt. At the end of the city, to the right, there's a Shop. There's a new sword here, the Fang Saber. If you can, buy one for Brian or Ain. The southern gate of the town is closed, and Brian must talk to the Mayor so that he can open the gate. There's a bar next to the shop. Enter and talk to the woman and she'll tell you that Arnos has been up to his old tricks again. The woman will ask you for help. Now go to the second floor and talk to the guy. He'll tell you Duncan's story and will ask you to visit him. Duncan drank the water of the river and became a Demi-human. The house that's next to the northern gate (to the left) is where Duncan is being kept. Talk to his friend and go see Duncan. He'll become violent and escape from the prison to attack the people but Ain will stop him; then the Mayor will say that he wants to speak to Brian and Ain. The Mayor's at a building just south from Duncan's cell, at the second floor. After you talk to the Mayor you can leave the town. Move to Spitt Plains to fight.
The old Christopher will join the party, although he starts out as average, he'll be a very good unit later, as strong as Brian or more (of course, not better than Brian :-P). Meanwhile, Arnos is seeking for revenge. Move to Spitt Rivermouth.
Now move to Rubens Road and, yes, you'll have to fight again.
The battle is over, but the Demi-humans keep coming. Loise, a member of the Liberation Army, will appear and use a gas that returns Demi-humans to normality. Loise is going to tell Brian and Ain the details of the processing plant. She only tells that the men of the village were forced to work and at the same time, a monk called Ryoukan appeared and he had abducted all the women of the village. Loise will tell Brian and Ain the rest of the story if they rescue the women from Ryoukan. Move to Rabi Castle, where Ryoukan has all the women (they don't seem to be very sad X-D). After a little fight, he'll give up to the women and give Brian the key of the research laboratory and if your emblem is Chaos, Ryoukan will join you. He's an excellent unit and you should use him always. Return to Rubens Town and talk to Loise. Now that they have the key they'll save the men and Brian will be the decoy. Leave the town. Brian will be captured by imperial troops, as planned. In the prison, talk to Shane, the birdman that's at the end of the room. Then escape.
Brian will lower the bridge and Ain and the rest will arrive to help. Loise will join the battle.
Enter the research facility, where Arnos will give Brian a warm welcome, I mean, he'll receive you with a new battle.
Enter the next room to face Arnos once and for all. He'll not give up and will release his Demi-human army to attack.
Loise got the formula for the antidote but Arnos escapes. Follow him moving to Imperial Army Gate. Here, Arnos' own creations will finish him off. Then move to Rubens Town. Now the shop is open and you'll find a new sword and axe. And there's a Leather band too, but is very expensive. The shopkeeper will give you some Rations and 3 Mind Repairs. You'll find these in the Storage. Go to the house where Loise was at and she'll introduce Ain and Brian to Koumei, who will offer Brian and the rest to become resistances. Brian and Ain refuse because they were imperial soldiers until few day ago; they tell Koumei that they're heading to Yanick Port. Leave the town and move to the Imperial Army Gate again. The Liberation Army cleared the road to Ragu Valley. Here, Brian and Ain meet Loise and Koumei again. The big news are that Brian, Ain and the rest were assigned to the Third Guerrilla Unit, they, Loise and Shane would escort Koumei, to his destination: Yanick Port. Brian and Ain have no choice but to give up.