After you have beaten Hard Mode, you will unlock Very Hard Mode. Once again, you must beat all 20 missions to unlock this achievement.
It is highly recommended you have a fully upgraded health bar, devil trigger, and maxed out Royal Guard style to beat this. You will also need plenty of holy water, Vita stars and gold/yellow orbs, so you may want to invest a good amount of time orb farming before attempting this.
Very Hard Mode Stats:
Lesser demons and bosses health: 200%
Lesser demons and bosses damage: 200%
After beating this mode, you will be rewarded with Super Dante or Super Vergil.