I honestly hate this manga. Every character is unlikable. Even MC (got tired of ruining lives, so decided to watch how their lives are ruining on sidelines) or his sister (manipulating everyone). Premise is good, unique but has no logic backing it up(even most magical ones are based on logic). For example how parents can let their children in school to become slaves (sexual or otherwise).
in 15 chapters, there is no growth, everything is the same as in first few chapters, just with different characters.
This manga is seriously bad.