The pregnancy tests in Japan are really not much different than those in Western countries, but ALL tests in Japan are only proven to be 99% effective if taken one week after the expected start day of your missed period. I believe most tests in Western countries are like this as well, although there are some that supposedly can detect sooner.
Some of the pregnancy tests in Japan have an explanation in English about how to use them, though, most of us can probably agree they are pretty simple to use. Just pop the cap off and pee on the stick part. Wait a minute until the results show up. If there's a line, or plus sign, or whatever the positive symbol is, then you know you're most likely pregnant. If it's there but slightly faint, then try again in a few days.
|Pregnancy tests in Japan: Clearblue, Check One, P-Check, and do test from left to right|