Social Insurance System for non-Japanese people

As of now, I do not have enough knowledge to support foreign residents, but someday I would like to do that kind of field as a Gyosei-Shoshi.
When I learned English in an English school, some teachers were interested in the information about social security systems in Japan. So, I checked the related information.

In the Japan Pension Service website, there are many useful leaflets to explain social security systems in Japan.
https://www.nenkin.go.jp/pamphlet/kokunenseido.html
https://www.nenkin.go.jp/pamphlet/201904.html

According to these leaflets:
1 All people who are registered to reside in Japan and aged between 20 and 59, irrespective of their nationality, must be covered by the National Pension system and must pay contributions.
2 The non-Japanese people, who register to leave Japan, can file a claim for the Lump-sum Withdrawal Payments.
3. Anyone living in Japan shall enroll in the social insurance and the way to enroll in is depending on their (or their family members’) working style.

To attract many non-Japanese people, these kinds of systems are very important. I would like to acquire various kinds of information related to foreign residents.