im pretty sure he's talking about the first demon in the slayer route. the slayer route is definitely harder than the demon route since the slayer deals less damage and doesnt get to buy items before the first quest after the tutorial battle. It also doesnt help that the lust meter works against us in the slayer route as i keep getting hit with an attack, fill up my lust meter, attempt to "lust attack" the boss, does nothing, then get hit with another attack (and if its an ultimate then i just take full damage, no chance to block). Frankly either allowing us to "lust attack" the boss, having the concentration breathing also regen HP, or being able to block instead of attempting to lust attack would make the fight a little easier.