The five-digit ID code you see tattooed on the children’s necks are used by demons to identify their livestock similar to cow tags on a farm.
Emma’s horoscope is Leo which suits well to her character for being sociable and confident. Also, green eyes are often associated as born leaders and intelligent which Emma exemplifies.
The three main voice actors of the show are also known for their other works such as Nina from Rage of Bahamut as Emma, Hiyori from Noragami as Norman and Killua from Hunter x Hunter as Ray.
The Promised Neverland and Dr Stone were the two manga who came out from nowhere and climbed the top of the magazine ranking in less than a year.
If you’re wondering what was the meaning of the six-digit number at the beginning of the show, it’s actually the calendar date of the current episode.