There is this manga about a constructed environment where people lived like it is feudal japan governed by weird priests and 4 gods in 4 corners of the world, unknowing to the fact that the outside world has high tech. One of the rule within this world is removing people above the age of 40 or so that includes female mc's dad or grandpa so she started the quest to look for him.
The fake world is designed according to the childhood doodling of twins. One of them choose to naturally age to dried up wheel bounded old hag and the other stopped aging given the high tech and stayed young. The young looking one break into the fake world from time to time.
The female mc did find one of the old men from the same village and he hold her that he has been working in the junkyard disassembling airplanes ever since exiting the world.
The manga is serialized several years ago, so most likely it has ended.
I don't have cool rewards.