Were any of the manga real titles?

While watching the movie I was curious about if any of the manga we see on screen is from a real manga. Obviously, I know the first manga they read is made for the movie (and that they eventually created a live action miniseries for that as well), but the other manga we see, are they also only made for the movie? I'm really impressed with their art budget if yes! And if they are fake... some of them look kind of familiar. Are they references to manga that were popular at the time?