Plot/Story
Taking a look into the past is the easiest way to protect the future. Mankind's technology has advanced far into the future where people taking looking into someone's past literally. A nasty flood almost destroys an entire city just days after their new dam was built. Looking into the memory of an old citizen from that city, engineers can recall that information from any host to understand the real story behind the flood.

Not a very easy story to follow and especially more convoluted due to its backwards-progressive storyline. Considering the ending, if author Osamu Akimoto had pursued and extended his take on the flooding disaster the story would have been a lot more interesting. And when we have uninteresting characters and no real backbone to a story, a twist ending isn't going to surprise us in the least, in fact, it may complicate the story to the point where a reader asks him/herself if what they just read made any sense.

The story still scores points for suspending our follow through of a young girl, her city and their concerns with a pummeling flood approaching. The experience seems to be real, even if it doesn't have a specific type of perspective.

Characters
We learn a few characters by their names, but no one in particular stands out from the city. Apart from the courageous type, the cowardly type and the aggressive type we're handed nothing but faces to go with majority mentality. We stick with the 'main character', if you can label her as one, throughout the story, growing her up and placing her in newer settings.

Drawing Style
A few brilliant portraits of realistic perspective and some nice oval shaped Caricature thrown into a single story. I'm sure Osamu has done this before, but I'm not sure how he could get away with it. The blend in background, and the lack in blend is pretty noticeable when comparing pictures like a well designed dam to a botchy figured character.

The fusion of the character art and the background is one of my biggest concerns. In most cases, Osamu is happy simply drawing foreground extras, things like chairs, desks and perhaps giant boulders, but seeing those together with a portrait of an entire floating space station makes the characters look ugly in comparison.

Enjoyment
I assume you'll enjoy the ending. Not because it's happy but because you're relieved to see some development in plot, before it all ends. It's seems hard to enjoy a story as predictable as surviving a flood, even more so when you have no comedy relief, and placing it into a category of genres doesn't seem at all sensible. But you'll enjoy the suspense, not matter how short it lasts.

Overall
I can only guess what Osamu was thinking when writing this up late at night, and even then I'd still guess the answer wrong. Unnecessarily wordy for little character development, and a hidden premise for readers who want to keep reading until the end, I suppose you can understand Osamu's target audience, no one old enough to read deeper more meaningful stories, but we have to appreciate a guy who can write One-shots for a magazine that's also running his serial in the same week.

What can I say Osamu? Oh, well.