This game has a pretty impressive twist. The cleric character is actually a bandit trying to lead weak adventurers through the trials so they can have weak people to fight and then continue being bandits.
The only way to unlock the true ending is to use the cheat whistle once, then the cleric will ask Rusha if she believes someone who has done bad can be forgiven and if you say yes he helps you fight the bandit ambush. Later on you take on the bandit stronghold and the cleric puts the main girl in a skimpy "magic" armour outfit that all of the fellow adventurers like. Then he takes her clothes off during the final boss so he can't focus and the cleric beats his ear drums so he can't dodge anymore.
Unfortunately this game does not have an ending where Rusha has sex with her fellow adventurers unlike Itsuwari no Yuusha Ceresu (false knight celes)
If you only speak english, dl texttractor and use that, makes the game easily playable.