No. 6 was the first manga series I ever finished back in middle school, and I wanted to reread the series to see if it still held up. And so far, it absolutely does! I still haven't read that much sci-fi manga, so No. 6 stands out for me. It has an interesting premise, although admittedly it is not the most unique it is still fun to read. What really drives the story, however, is the characters. And Rat and Shion are fantastic protagonists. Plus the art/character designs are great. Fingers-crossed that the rest of the series holds up