Meruem

Meruem is the King of the Chimera Ants, an insect species that takes the traits of whatever it eats. His mother consumed humans in bulk so that he would be born with human intelligence, and he arrived early by tearing free, killing several of his own guards on the way out. Within days he can read a language after glancing at it and beat a national champion at any game he tries.

Then he meets Komugi. She is a blind girl, malnourished and awkward, and the reigning champion of gungi, a board game she has never lost. Meruem plays her repeatedly and keeps losing. The King who was built to rule every living thing cannot beat one starving human at a game, and the part of him that finds this fascinating rather than intolerable is where the arc turns.

Readers argue about a lot of Hunter x Hunter. They mostly do not argue about this. The Chimera Ant arc runs long, slows down, and spends its final stretch on two people playing a board game in a quiet room while everything outside falls apart, and it is the sequence people cite when they claim shonen manga can do something else. Togashi took a monster and asked what he would become if left alone with someone kind.