An image from a 2018 article about the plan to deploy JGSDF to the southern islands. Three of the islands (Amami, Miyako, and Ishigaki) will have both anti-air and anti-ship missiles.
The deployment of those assets to Miyako island was completed in March 2020.
An image from an article from April 2019 about upgraded Type 12 missiles planned for deployment by 2023. The image shows to difference between the range of the current Type 12 missiles and the range with the planned improved Type 12 missiles from Miyako island.
JGSDF page about structural change from static local regional divisions to what is called "mobile divisions". They are being structured as such to enable divisions to react to reinforce the southern islands quickly.