This is from a highly rated very western-friendly Japanese anime franchise.
It is an example of an "OVA" (Original Video Animation), usually a "short" that exists alongside some full length movie, movie series, TV series, etc. This one is just over 3 minutes, a mini-story.
It opens with 3 kids who seem very familiar but somehow different. These 3 kids look like people we have "lived with" (through the main story) from very, very young through about 18 years of age through some serious stuff. That story (largely) exists within a parallel universe to ours, beginning in their 1899 to 1905. The starting year is vague, because, reasons.
So here we have these 3 kids we think we know. They cross a field into a small city, but when they arrive they are in a modern city of the year 2005. What's this?
Turns out they are looking for Great Grandfather on his birthday. As they get to his home we cut to an old man, vaguely seen but somehow more than vaguely familiar looking!
He lays down a photo of two brothers, two brothers we know very, very well. In the photo the boys are somewhere between maybe 19 to 25.
We hear the kids arriving and jabbering, calling out. But we notice the old man's "automail" (prosthetic) hand and arm. This is the main character of the main story, one of the brothers in the photo. Not his Father at all, despite the resemblance.
A subtitle appears, saying this is 2005 and he is 100 years old.
Did his devoted year-younger brother survive to old age with him? What about his wife, who the little girl resembles so much?
Such a gut-punch to me. I've seen the two TV shows and two movies many times, but I just discovered this OVA.
Am I wrong? Should I shrug this off and feel nothing? How stupid am I getting in my old age?