For the Shadow Mission, see Soul Stream (Shadow Mission).
The Soul Stream is where Nao resides. Numerous owls are seen flying in the area. This is also where the Added Soul Phenomenon occurs and Nao is able to direct the souls of those from other worlds, Milletians, to Erinn. It connects to all of Erinn and therefore anyone in the Soul Stream can come out anywhere in Erinn. There are other Soul Streams for other worlds.
Players go through the Soul Stream during their birthday (the character's original creation day - not necessarily Saturday, the age-up day), the Rebirth process, and the April Fool's Event.
In the birthday, when the player logs in, Nao will appear and give them a random accessory. Players can talk to her with the Keywords they've gathered throughout their journey.
For the rebirth process for a Human, Elf, or Giant, Nao will appear, aiding them through rebirth.
When rebirthing as a Pet, Tin will appear in Nao's place and follow the same procedures as if rebirthing through a humanoid character.
During the April Fool's Event, when the player logs in, Ferghus will appear in Nao's place, giving them a Ferghus's Free Repair Coupon.