>>281958256
They were, in retrospect, good memories to Yoshida who has been a government lapdog all his life.
The theme of the chapter is "Role", Yoshida ends up looking back on his role as Denji's guardian as a much fonder memory compared to the "role" he is playing now, as a detonation switch, possibly leading to his death.
He just didn't realize how good he had it at the time compared to the current state of things.