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|
Pregnancy test in Japanese is: 妊娠検査薬 (にんしんけんさやく, ninshin kensa yaku). Although you may also see it as 妊娠判定テスト (にんしんはんていテスト, ninshin hantei testo).
The main brands you'll find in most daily goods/drug stores are:
Check One (チェックワン)
do test (ドゥーテスト)
I've seen one called Blue Sign S (ブルーサインS), but only in some stores, and not so much online.
Check One and P-Check also offer digital versions, although those are slightly more expensive than the non-digital ones. You can typically buy a single pack, or a pack of 2 for all these brands (and really, the pack of 2 is a much better deal, price-wise). None are really too expensive - a single pack will run around 600 - 800 yen or so, while a double pack could be 900 - 1400 yen, depending on the brand. Is one any better than another? Not that I know of. They all test hCG levels, and from looking at all of them, doesn't seem to be much of a difference between them, aside price.
Of course, if you ARE pregnant, you may want to check out the "Pregnant in Japan" series:
Pregnant in Japan: Resources
Pregnant in Japan: How to find a doctor, hospital or midwife
Pregnant in Japan: Visiting the Doctor and What to Expect
Pregnant in Japan: Diet, Nutrition and Weight Gain