@Metazoxan
There is never any implication that the people at Relife were just a bunch of heartless, corruptive a-holes trying to scar people. The whole point was to help people who are NEETs be rehabilitated back into society. The memory erasing is just to remove the suspension once the younger versions of the subjects disappear and help keep company on the down low.
Technically, it has been mentioned that the mediacal professionals at Relife only were partially certain that the memory erasing was irreversible. Everything was experimental, so they weren't certain what would happen until the end of the experiment.
This concern was only focused on Arata and Chizuru because of the connection they have. Since they were both Relife subjects, both already aware of the program, there should be no problem with allowing them to both keep their memories. However, since this is the first time they've had two subjects during the same experiment, how to possibly reverse the memory erasing effect was scientifically unknown.
The returning of their memories, however, is actually no different then regaining a memory that you haven't thought about in years just suddenly hitting you. So it can be assumed that the memories aren't actually erased but repressed; lost somewhere in the brain. I mean if you experienced having the same phone strap as somebody or recalling things you heard in the past during an event that you remember being at, wouldn't it start to jog some thoughts of that person, even if it's a memory you forgot about a long time ago?
