S P O I L E R
After a few dramas, Sei & Aresh are ENGAGED.
Aresh found a way to open a portal to Sei's world, but It will takes a long time because it requires a lot of mana AND MONEY. He told Sei if he wants, Aresh will help him to get him back to his world, "I’ll also find a way to come to your world, even if it might take a long time."
But in the end, only the Saintess returns. According to Sei, the Saintess is still underage, so she has to go back to her parents on their real world. Meanwhile, Sei stays there because he’s an adult, so he can do as he pleases. He's afraid someone might cry if he goes back (aka Aresh).
A few years later, the now-adult Saintess returns to the kingdom and marries the Crown Prince. Sei & Aresh? They are also planning to get married and will have their honeymoon in Japan.
It supposed to be R19 story with few of snu snu scenes and it's very hottt . Sei is kinda naughty ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄
And I like the ending