The boy in the first life lived happily with humans
In the second life, the boy lived happily with humans, even if humans had no memory of their previous lives.
The third generation boy looked at the humans without memories and used it as a bed warmer.
The boy in the fourth life is still with human, but this time the human remembers these three lives.
The boy in the fifth generation is tired and humans can't find the boy.
Keep forgetting but remembering again, no matter who it is