Spies are a very real part of the world, yet they're not something a person tends to see or hear about every day: they wouldn't be very good at their job if they were. This sense of enigma feeds into the common imagination and gives stories about spies and secret agents a powerful draw. While they may not be the most popular anime subject-matter, spies have nonetheless provided some of the most interesting, action packed and enjoyable stories in anime.
Source：https://www.cbr.com/best-anime-spy-shows-that-are-not-spy-x-family/
