It is a very common error to try to get the time in other timezones by using offsets from your own timezone without allowing for the fact that the offset might vary depending on the time of year. I assume you know about setting your clocks an hour ahead for part of the year.
The time in Japan is always (for twelve months a year) nine hours ahead of Greenwich Mean Time, if I remember correctly.
Try this PHP command:
<php echo 'Tokyo time: '.gmdate('Y-m-d H:i:s',time()+(9*60*60)) ?>