At first I thought this manga plot had a potential, it could have taken a full-on philosophical thriller route questioning about the value of life and if it is worth living in suffering, but nope it fell flat out average.
Yet there are so many unexplained questions.
It's almost irritating to see such wasted potential, I wish to read a manga with such ideas.

Story: 5/10
As I mentioned earlier, it was flat.

Art: 6/10
Artwork was decent, surprisingly no gore.

Character: 6/10
If you removed Bando (female character) from the story, it wouldn't make any difference, ironically "She is not needed". The story could have continued with Chiko getting blackmailed and desperately trying to save everyone.

Enjoyment: 5/10
It was short, so yeah its fine, had it been long would have dropped it.

Overall: 5/10
Check it out, you have nothing to lose.