Finally managed to track down Battle Angel Alita: Last Order 112 and 113.
Kishiro's catching us up with a trip down memory lane through Figure Four's point of view. Starting from his village - which we see for the first time - to following the remnants of the Barjack.
Of course, how this plot thread meets with the current story happens in a way one would probably expect.
end of spoilers
Figure Four fights Sechs, over her murder of an AR-Unit he mistook to be Alita. He is her superior in fighting skill, but ultimately loses due to trying to grapple with a cyborg using a human body
After escaping the fight by diving into the river, he's washed up in a Factory Farm village with the body of AR-4...and is saved by Daisuke Ido.
So very fanservice, and a welcome sight for sure. But I want them to get their asses to Mars already. I hope this plot thread goes somewhere substantial.