Too Bleak, Stopped Caring: It is, without a doubt, Osamu Tezuka's darkest work, barring possibly Ayako, and it shows. Our main "hero" is an outright villain, with other characters not being much better, and those who are genuinely good going through horrifying breaking of their spirit and the ending almost crosses over the Kill Em' All territory. The nihilistic and despairing tone can make it a very difficult read, specially for those who know Tezuka for his somewhat-bittersweet-but-still-hopeful creations like Unico, Kimba, Black Jack, and Astro Boy. Ironically, Tezuka himself agrees that he went too far with the dark tone, with him disliking writing characters like Rock.
