[ From what he can tell, seeing how this is the first time he has heard this, yes, it's rare. But speaking for himself...in comparison Tenka had the sort of personality for attracting people....so for them to come back and not remember the acquaintances he's made--

He can't quite imagine it. People coming up to you and saying they knew you. He hadn't needed to go through that. ]

Should he return, he has you. [ Saitou pauses, as he tries to find the words he means to say. ] With or without memories, the company of someone familiar is very reassuring. [ He stops again. ] I apologise if I'm speaking too forward about this. [ Seeing how he hasn't known either Sousei or Tenka beyond a few weeks. ]