Indeed, the Spirit Stream wasn't far away. All Rean and Kentucky had to do was continue heading west. Since they knew that a Spirit Stream would be close to the Azure Lilibel race's territory, it also meant they would find it sooner or later. That's exactly what happened a little over half a day into the journey.
"Oh! This thing is definitely huge!" Kentucky hadn't seen it before, so he was quite impressed.
"Alright, you can admire it another time," said Rean. "Follow the Stream until we find a Spirit City that has an entrance into the Stream. We need it to cross the continents on our way to the demon beast territories."