Yeah I thought my 1st playthrough was the entire game XD it's definetlymy favorite game of 2017 atm, especially the final fight between....you know, but I got the 9S ending so I ended up all teary eyed XD
Probably my top 3 favorite games of all time for modern gen consoles
1. NG series
2. Nier
3. Last of Us
Did you go back and do the other ending as well? If you do both, you unlock the "true ending" which is "E"