Two suggestions for Japan if they would like to save energy.

1) Start using daylight savings time -- right now, Japan uses the standard time all year.

2) Join an appropriate time zone in the first place. Tokyo is in the same zone (UTC+9) as Korea.

As a result of this, in Tokyo during summer, it starts getting light out before 4AM, and the actual sunrise is before 4:30. I live in Tokyo and can tell you this is almost as traumatic as the summer humidity.

The sun never almost never sets later than 7:00 and seemingly everyone here stays up under lots of electric light pollution until the last train rush around 11:30-12.

So additional ways for Japan to save energy and be less reliant on imported oil do present themselves imho.