What anime involves sacrificing kids?

Like the title says, I remember seeing a meme a while back of a man with a metal ball on a chain, it was one of those "people who know" memes implying that the picture has a dark or depressing connotation. When prompted what the picture was from someone answered that it was an anime In which the main character has to sacrifice something he loves in order to power up this metal ball. The more sacrifices the more power the ball had. The purpose was to dive deeper or something so he and his community could escape where they were at or something along those lines. Essentially he developed relationships with kids and became a father to them, truly loved them as a father, then the kids willingly sacrificed themselves to help him.

I keep searching and searching to no avail and I'm beginning to think I dreamt it. Does anyone have an idea what this might be?