An assassin who cannot kill x a blind young man

"If you knew the real me... you'd be disappointed."
Born into a family of assassins and living in a world of darkness, Chinatsu has been unable to kill anyone due to his past trauma.
When Chinatsu's brother died before his very eyes, a boy reached out a hand to him.
That scene is still burned into his mind...

While having the same nightmare yet again, Chinatsu happens to see the boy from that day, Kasumi, again.
Unable to leave the blind boy alone, Chinatsu unexpectedly becomes his "friend", but... Chinatsu, who suffers his family's curse, and Kasumi, who despite his blindness is spirited and pure.
This is a story of salvation that melts the loneliness of two people living in darkness.