@HYBRID_BEING regarding why demi-humans are needed to become slave, is because normal demi-humans can't just operates freely in the country. For the detail, ch 34 explained it.
@NotTriton Sorry, you're correct. Yari no Yuusha no Yarinaoshi starts at 410 and goes to 835. Shin(Real/True) - Yari no Yuusha no Yarinaoshi is from 836 onward... Just quickly checked it without double checking as I haven't read the side story having finished the main story in 2014
Ah yes Gacha addiction, calculation by pull rates becomes a first XD. Also I agree with the comments above, the likely reset here is with Ren getting killed with how the King kinda knows that Ren is being suspicious with him and Myne.