This is not a standard manga, whose purpose is to provide fun light reading, mainly for kids and teenagers. It's more like a long serious novel, whose purpose is to move adults emotionally—in this case by telling the story of how several characters grow into adulthood. That's a big job, and I imagine Toume Kei took it on in part because she knew her drawing skills were strong enough to depict characters realistically and hold readers' interest in them. The fact that the manga continued to run in Japan from 1997 through 2015 suggests that she achieved her goal in that respect.
The story can essentially be summed up by saying that it's about a love quadrangle. There are two young men and two young women, just starting out in life after school, and we follow them as they try to discover who will marry who and what each will do as a career. Not easy for them, and more so for us at the beginning, because none of them seem to know much about the opposite sex, and of course we don't know anything about them.
Lots goes on, and eventually who will be with who is decided, and in the process of reaching that outcome the characters learn lots about the opposite sex, themselves, and each other, and we the readers take a long, suspenseful roller coaster ride. The story is that simple.
But the characters are the opposite. They are complex and determined people and as such they are very interesting and often mysterious. Why is she doing that? Why is he that dense? Etc. It's a lot like real life, where you can never get the real lowdown on the people you know and care about. And that's the essence of the greatness of this story. It uses manga to tell a completely realistic story and tell it well.
In short, this is a highly realistic depiction of serious young Japanese people as they pass through the most crucial early stage of their lives, and as such it's a very absorbing read.
