Tha Japan Government announced the scheduled blackout and it starts from 14th of March in Tokyo, Kanagawa, Chiba, Saitama, Ibaraki, Gumma, Tochigi, Yamanashi and Shizuoka.
The blackout time and area is depends on the Group where you live.
The train service will be affected by this blackout, so please take care the time when you go home.
The blackout will lasts until end of April.
You can check the Group in the following list.

List of the Group of the Blackout(Japanese)

Blackout time
Group 1 6:20~10:00 & 16:50~20:30
Group 2 9:20~13:00 & 18:20~22:00
Group 3 12:20~16:00
Group 4 13:50~17:30
Group 5 15:20~19:00