Art, however, requires plot to make a story come to life. As I've said, even children's Japanese comics and animation deal with things like death. They also show that one's enemies aren't Just Evil. In series like Gundam, you can see that the enemies have hopes and dreams of their own, and do, in fact, have reasons for what they do. They aren't just crazy, or just plain evil.
Actions have consequences.
And, like all good stories and all real stories, manga and anime have a tendency to end. Heroes and heroines die, or get married, or disappear. The anime series are especially good about this. Of course, the anime or manga is often carefully crafted to either jerk tears out of your eyes, or make you stare in wide-eyed absorption to the very very last line of the credits. I can't describe it here, but think of the ending to any truly good movie, and you probably have it.