This is the first in a series of manga. If you are unfamiliar with manga, it was a form of Japanese comics. Although it started in Japan, it moved on to China (manhua) and South Korea (manhwa). It then moved on to the USA, Canada, and France, to name just a few. The first were translated, but artists from the Western countries went on to create their own manga. For more details look up 'manga' under Wikipedia.
Some people don't consider manga art. That's your problem.
N.G! is one-shot. There are more strips, but since they are separate pieces, I'll only consider the first. Nakatomi is a high-schooler, but since they have good art books, a nearby university bookstore is where she is shopping. As she moves to the racks, Okasabe eyes her. After hesitating, Okasabe her to a fancy restaurant. Even so, she's still creeped out a bit. So she talks to Rin, her twin. By the way, Rin is TG. Hilarity ensues. End of story.
Since N.G! is a relatively short story, this will be brief. Good side - N.G! is true to form, with Okasabe being kind. Bad side - translation fairly poor, with the viewer being somewhat confused about Rin's identity.