I remember a manga I read a few years ago that takes place after the apocalypse, with one male character and several female characters (who all kinda bicker over him a little). The adults and almost everyone else have vanished from the planet, consumed by dark abstract monsters. However, the manga itself was very calm and slice of life, with the kids raising crops and cooking and doing laundry. Some of the city is flooded and they go canoeing through the streets.

I stopped reading it at the time because I got fed up with the kinda creepy fanservice and wanted more worldbuilding and details about the monsters and survival techniques, but I'm curious to know how it ends now.

Does this remind anyone of anything?

(Alternately, is there anything similar to Yokohama Kaidashi Kikou in tone and subject matter that I could read? I also really loved Donyatsu.)

Chikyuu no Houkago?

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~4400 manga completed
~1700 ongoing...

For post-apocalyptic slice-of-life:

Shoujo Shuumatsu Ryokou

Jinrui wa Suitai Shimashita (Novel) started out to be promising, but as it's not fully translated and will likely never be, I recommend the anime adaptation, which is quite nice.

@Aremon: Yes, that was it, thank you!

@calstin: That first one is bookmarked for me now (mostly because it reminds me of The Sound of the Sky meets Kino's Journey), and I have Humanity Has Declined in my crunchy queue. Thanks!