Known to many countries across the globe, the Land of the Rising Sun is currently experiencing a workforce setback as a result of its aging population and low birth rate over the years. Consequently, quite a number of industries and sectors in Japan are highly affected by the issues on chronic labor shortage.
The fourteen identified fields that are said to suffer the worst forms of labor problems are as follows: nursing care, building cleaning, material processing industry, industrial machinery manufacturing industry, electric and electronic information related industry, construction, ship building and ship-related industry, automobile maintenance, aviation, lodging, agriculture, fisheries, food and beverages manufacturing industry and food service industry.

Except for construction as well as ship building and ship related industry, all other twelve sectors mentioned above fall under the first category known as Specified Skilled Worker (I). Under this category, potential foreign workers are expected to possess skills that need only a certain degree of knowledge or valuable experience in relation to the specific industrial field that they are planning to apply to.
On the other hand, Specified Skilled Worker (II) category which covers the construction and ship building industry requires that the applicants have expert skills and experience in the field. In order to successfully land in this category, it is essential that the foreign national must complete and pass the industry specific exam.
For Specified Skilled Worker (I) category, there is another way for foreign nationals to qualify aside from passing the exam. That is, to complete the technical internship training program. In this way, foreign nationals are no longer required to take and pass the industry specific exam.
Foreign nationals who are qualified under the Specified Skilled Worker (I) category, they may stay in the country for up to five years with renewals every one year, six months or four months. Meanwhile, successful applicants under Specified Skilled Worker (II) may stay in Japan for a period of three years with allowable renewals every three years, one year or six months.
Reference: What is a “Specified Skilled Worker” Residency Status?