For charts and frequencies go to
https://aisjapan.mlit.go.jp/Login.do. Set up a free account, which goes inactive six months after your last login.
From the start page, select AIP from the menu bar near the top.
Select the desired effective date.
On the left side under Part 2 select ENR 2 Air Traffic Services Airspace. Sector IDs, frequencies, and boundaries are listed. Scroll down the right side near the bottom and find links to PDF maps in figures 67, 68, 69.
On the left side under Part 3 select AD 2 Aerodromes. Select a desired airport. Select AD 2.17 ATS Airspace, or scroll down the right side to get to the same place. If an airport has both Tower and Terminal, there will be a link to a Terminal airspace map, ...APPROACH_CONTROL_AREA.pdf. AD 2.18 has lists of frequencies. I haven't found any details about how Terminal airspace is divided between Approach and Departure functions.