In raw numbers, Japan recruited an estimated 1.08 million foreign workers to edge out the 960,000 of the ROK even though its population of 50 million is less than half the size of neighbouring Japan.
In other words, the proportion of foreign workers in the ROK is more than double that of the East Asian island nation.
Foreign workers had entered through the Industrial Training System, which was akin to the current Technical Intern Training Program of Japan.
However, Seoul replaced that framework with a broader Employment Permit System in 2004, which has since allowed 480,000 nonprofessional workers entry into the country for work purposes.
Among the number, the ROK granted regular work permits to 260,000 people from Vietnam, Thailand, Cambodia, the Philippines, Indonesia and 11 other nations under bilateral agreements.
They generally work in agriculture and for small manufacturers. In contrast, Japan has taken in only 210,000 technical recruits.
The number of nonprofessional workers accepted increased sharply after the introduction of the Employment Permit System, said Koji Sano, a professor at Fukushima University and expert on the labour policy of the ROK.
What sets foreigners working in the ROK apart is the sheer number who have learned to speak the language.
Some 220,000 people were recruited through the special work permit system— among them ethnic Koreans from China as well as other foreign nationals of Korean heritage, substantially all of whom have the ability to speak the language fluently.
These workers can be found predominantly working in the service segments of the economy, such as restaurants and nursing care.
Meanwhile, the language barrier has prevented Japan from attaining and retaining higher levels of recruits of talented foreign workers.
On the other hand, Japan has been much more successful at recruiting younger students. There are currently approximately 210,000 foreign students in Japan compared to only 13,000 in the ROK.
Right at 80% of these students have joined the work force in Japan while only 10% of the students in the ROK are in the work force.