If you want to feel the same 90’s nostalgia from “Analog Squad”, then you should definitely watch Reply 1997.

Both dramas have a very similar plot. The only difference here is the target of the main character’s next target.

Both dramas have a similar concept. Both main characters use a device to contact a person from another time. In Kairos, it is a person from the future whereas in Signal it is a person from the past.

Both of the main characters decided to adopt a new identity and embrace western culture. Also, both characters use guns... a lot. I guess those are the things that make both dramas similar.