Explained with unusual rigor specifically so later arcs can show characters bending or exploiting the rules in complex ways.
Widely considered the series' peak — tonal shift into morally complex territory, centered on one of the genre's most-cited villain arcs (Meruem).
Deliberately subverts genre expectations rather than delivering them straight — know this going in.
It's better as a second or third shonen series rather than a first — its value comes largely from subverting conventions that a genre newcomer wouldn't yet recognize as being subverted.
It shifts the story into unexpectedly morally complex territory and is centered on Meruem, a villain whose character arc is frequently cited among the best written in the medium.