After Ben awoke from his fainting, they all immediately set off for the Summer Region, and Ben is now being their hostage. Actually, only he thought he was, as no one explaining anything to him. They just keep him in the dark like a punishment for the wrong deed he done before to Jieun and Mia. And now he just obediently following them on that journey.
They actually just brought him together as he is one of the local there. To not raise too much suspicion from the villagers there. That's their only reason actually.
About three days they are travelling and finally they reach the Summer Region. Just like its name, the land is on summer all year, but it's not like it unpleasantly hot there. It's just right with a soft breeze there. The land also has rain, but even when its raining the temperature is not as cold as in normal land. It's raining, but the sun still shows itself. Just like that.