Neko to Spica

Salaryman Kawamura Kouta hates troublesome things. The only exception is the black stray cat that likes to sit in front of his apartment. One day, he stumbles upon a black-haired boy who seems to have replaced his favourite cat. When the boy collapses in front of Kouta, he decides to take him in on a whim. What will happen to Kouta's trouble-free everyday life?