Similiar to all Tri-Ace Games, Seraphic Gate is a additional extra dungeon that players can explore upon completing the game. It's only available by saving in the game's last save point on the hardest of three difficulty levels, and Flame Jewels found in dungeons exclusive to that difficulty level are required to access sealed rooms with unique treasures and hidden characters. The Seraphic Gate is a very long and tedious dungeon. The only save spot is in the first room, and four distinct sections and you must traverse back to the beginning in order to save, even after defeating optional bosses.

There three obtainable characters in the Seraphic Gate, Freya, Lezard and Brahms. They can be obtained by defeating them in a battle. The dungeon also features previously defeated bosses as random encounters, the best weapons in the game as well as Iseria Queen and Gabriel Celeste as incrediably strong optional bosses. Both optional bosses are replayed by saving and reloading the dungeon. Each defeat of the Queen after the first will provide a book of riddles. The tenth one will drop 'Angel Slayer', the most powerful weapon in the game, though one with a hit trust of 1 which translates into attacks that might do 10,000 damage one turn and 5 the next. Finally, Seraphic Gate contains the enemy 'Hamster'. Extremely rare and fought in packs of four, they are the most formidable and difficult enemy to kill, mainly due to the fact that most characters' attacks will miss.