Here is the full list of all 10 Grotesque Tactics: Evil Heroes achievements.
Defeat the REAL boss
Find a bonus mushroom
Convince Rukel to give back his loot
Find enough maidens for Holy Avatar
Be polite to Synthia
Survive the special tutorial in Station Wish
Save Mandy's chocochick
Add Holy Avatar to your party
Kill the first mushroom
Find all bonus mushrooms