Tides are determined by the gravitational pull of the Sun and Moon, and in certain cases low and high pressure weather systems (depending on strength).
If a site is directly below the moon or opposed to the moon on the earth, then it is high tide
if a site is 90 degrees opposed to the moon, then it is usually low tide.
When the sun and the moon are aligned, IE
Full moon or new moon, you get Spring tides, which hare the highest, and when the moon is haflway through the process, you get the neap tides which are the lowest.
So to add to all that, if a strong low (Noreaster/Hurricane) hits during a Spring tide at high tide, you will get a very large storm surge, but , but a Spring tide at low tide, can be good news and reduce flooding.
Now to the question of Japan and SF
and tides. since SF
sits ar around 123 W, and Japan sits at 144 East, they are about 90 degrees opposed, so tides should be opposite appoxmimately. So high tide in SF
should be low tide in Japan.
Older than I just was ,and younger than I will soo be.