Secret Character-
To get any of these you must have Mustadio in your party, and you can only get these in Chapter 4.
Beowulf-First go to Goug Machine city, there will be a scene with you, Mustadio, and Besrodio(Mustadio's Father) then go to Goland Coal City, Go in the Bar, and listen to the Rumor "Ghost of Colliery", after that go to Lesalia Imperial Capital, and When the knight asks you if he can come along choose the 2nd option "let's go together", then go back to Goland Coal City and Win the 4 Fights afterwards Beowulf joins.
Reis(Dragon)-Get Beowulf, after the battles you'll be able to get Reis
Worker 8- After getting both Reis and Beowulf go back to Goug Machine City, there will be another scene with you, Mustadio, and Besrodio, Worker 8 will then join you.
Reis(human)-To get this person you must have killed Adramelk and have Worker 8, also you must go to Zarghidas Trade City and buy a flower. Go to Goug Machine City and there will be another scene with you Besrodio and Mustadio. Then go to Zeltennia Castle, enter the bar, and listen to the rumor Cursed Island, Nelveska. Next go to Nelveska Temple and win the fight, afterwards Reis will turn into a human.
Cloud-After getting Reis(human) go back to Goug Machine City where another scene will appear, afterwards go to Zarghidas Trade City and win the battle and cloud will join.