I should pay them a visit

When the group got out of the pub the first thing they did was head towards Hilda's place. While they were walking Valdel asked the question he wanted to ask Ren since he received the demon's horn from Shin. 

"Ren I wanted to ask this for some time now, how do you know Shin? Why does he feel like he was someone that knows you from a long time ago? Also, what does that message mean? Who is the fourth hero and why was he grateful to a demon lord?"

Valdel was pretty sure that Shin was this supposed fourth hero, but he wondered who the demon lord was in the story. Based on what he heard and assuming Shin really was the fourth hero, then that would mean Ren was the demon lord. But that shouldn't be possible, the demon lord the fourth hero knew should be as ancient as him. Ren was someone from the same village, and he was born from two human parents, how could he be related to a demon lord.