The Northern God is the thirty-fifth optional quest. It's a hidden quest and is not included in the "Total Quests" until it is discovered. To obtain the quest, the player needs to decipher the Mystery Note. The Mystery Note can be acquired randomly by killing wizards if the killing hero has 2000 or more kills, the player is playing on Normal or higher difficulty level, the quests Manifestation of Evil and Dimension Connections are complete and the total amount of quests complete is 45 or higher. If these requirements are fulfilled, every wizard has a 10% chance to drop the Mystery Note.
If the player correctly deciphers the note and follows its instructions, the quest is obtained and the player is prompted to find and fight Odin, who can be found at the top left corner of the map, near Ultima Weapon. If the player doesn't defeat Odin within a time limit, he will use Zantetsuken in a cutscene, killing every player. At this point, Odin recovers all of his HP and the fight must be restarted from the beginning.
Upon Odin's defeat, the players are rewarded with 150'000 EXP, 200'000 Gold, 40 Crystal Shards, 3 Megalixirs and Odin Materia. Also, the team Northern God is unlocked in the Battle Arena's Dimension Cup, where he will always drop a Megalixir upon being defeated.