Inuyashiki (いぬやしき) is a Japanese science fiction manga series written and illustrated by Hiroya Oku. It also has an anime adaptation by MAPPA.
The series is about the old man Inuyashiki Ichiro who is gonna die from the cancer. But one fateful evening, he is struck by a mysterious explosion in a public park, which is of extraterrestrial origin, and his body is replaced by an incredibly powerful, but still outwardly human, mechanical body.
For more information see the Wikipedia page.
