I am planning to visit to Jeju Island, Korea, for vacation (5 to 6 days). Is there any specific visa requirement for me because I'm traveling also to Singapore, Macau or the Philippines from Pakistan?
Republic of Korea Ministry of Justice has a new restriction on Jeju Visa-Free entry, restricting visa-free status to 12 additional countries, effective August 1, 2018.
- Egypt (Effective Sept. 1, 2018)
- Sri Lanka
- source - sorry, Korean (pdf version by Korea Embassy in Beijing, Korean too)
Since you are Pakistan citizen, you need a visa to enter Jeju Island and the mainland Korea. (PS: Single entry visa is sufficient to visit Jeju island and the mainland.)
This list of countries shows that Pakistan citizens do not need a visa to visit Jeju for up to 30 days.
You cannot visit other places in Korea without a visa.
[Please go upvote revi's answer, it's more up to date].