Visas are legally called "Sasyou".
As a general rule, foreigners landing in Japan must have a valid passport.
A valid visa issued by the Japanese Consulate, etc. is required for your passport.
Japanese consulates, etc. "confirm" that the passport possessed by the foreigner is valid and legally issued by the government agency having jurisdiction.
Then, the Japanese Consulate, etc. will make a "recommendation" that foreigners should enter and reside in Japan under the conditions stated on the visa.
Visas can only be obtained at Japanese consulates, etc., and cannot be obtained even if you try to obtain one in Japan after arriving in Japan.
Issuing operations are under the jurisdiction of the Ministry of Foreign Affairs.
In other words, a visa means that the Ministry of Foreign Affairs "confirms" the possession of a valid passport and "recommends" it to the Ministry of Justice (immigration inspector).
After entering Japan, it will be used up and will not be the basis for subsequent residence of foreigners.
"Renewal of stay" is commonly referred to as "renewal of visa" and is sometimes used as such.
However, there is no "visa renewal" and the "stay renewal" is correct.
Keep this in mind.