The Grail Mask is one of the four masks in the Graveyard in Yuri's mind in the original Shadow Hearts. During the Europe portion of the game, it will appear as a regular enemy when the Malice meter peaks.
If the player seeks to obtain the good ending, they must defeat the four masks in a certain order (after defeating Albert and Amon in the Nemeton Basement, but before entering The Float).
The Grail Mask must be defeated first.
If the player has obtained the Oath Grail from Joshua in the London Rat's Hideout in London (which also details the order in which the masks must be fought), it will drain the Grail Mask's power when you fight it, meaning that the hit areas on your Judgement Ring will be doubled in size.
Dark soul waiting for the moment the dark world opens up to the world at large. It represents the harmonixers worldly pleasures.
Dark soul that represents the Harmonixer's worldly pleasures. It lost against the Harmonixer's consciense. but defeat made it stronger.
This mask at the beginning of the turn will automatically tighten the hit areas of your Judgement Ring which can be an annoyance but if you have the Oath Grail then the effect will be reverse and the Judgement Rings hit areas will expand. This mask is fairly easy and can be easily killed by using special skills.
"Oooff, *pant*, *pant*, *pant*...C-come on, I'll get you for sure next time!" ~ Grail Mask
Having already been defeated by Yuri, he is pitifully weak, and will be defeated in less than two hits.
The four masks relate to Tarot cards; the Grail represents the suit of Cups, which is the symbol for water, as well as having the face of a fish.