He’s just explaining the whole situation to him in order from start to finish, before he saw Imu at the Reverie.
if we continue the flashback next chapter, then I’m sure he’ll bring him up.
doubt his memory was erased, because that would mean he would forget the whole Lulusia incident as well (which he didn’t, as he talked to Koala about it)
if Imu can just selectively choose to wipe the memory of his existence from any person’s mind, then there would be NO need to erase entire kingdoms for it.