If the player tries to get inside the cave before completing the first dungeon, the guard will deny the party access.
Aigis, accompanied by his students (Sol and Glaive) and his sister Diana, was sent by the king to the Temple of the Crystal. The only way to reach there is through this cave. On the cave's last section the party will save Elgo just in time from a powerful monster. After the battle, Elgo will join the party, accompanying them to the Temple.