Glas enters a portal after completing the challenge of the Immortal Han Hsiang Tzu. On the other side of the portal he enters a room with another portal in front of him. Upon throwing the Bravery Medal into the portal, he is met by the Immortal Lu Tung Pin, who tells him that he has defeated the demons of his past and morphs into his human disguise. Lu Tung Pin tells Glas that he must face his greatest enemy and teleports him to a circular room holding many pillars and surrounded on all sides by thick fog. Glas looks ahead and sees an image of himself staring back at him with an evil grin. The image lets out an evil laugh and attacks him. Glas is able to defeat his doppelganger and Lu Tung Pin brings him back to the portal room in the Great Pagoda.
Demon Glas will start the battle with whatever weapon Glas currently has equipped and will change his weapon to match Glas's if Glas switches weapons during the fight. Thus, the difficulty can be reduced or increased depending on the weapon Glas equips. Carrying a fast weapon like an Assault Rifle makes the battle a good deal harder to to the increased difficulty in dodging. Weapons like the RL 480 or SS 2000 are good choices to bring in battle, because despite their higher fire power they are easier to dodge. Use a roll at the beginning of the battle to avoid Demon Glas's initial attack and run around the pillars for cover. Keep hitting him with heavy firepower and roll quickly when Demon Glas fires back. Four shots from the RL 480 will bring him down on Hard mode.