To do the self-shaken, you need to pre-book a timeslot. This doesn't seem to be binding, but rather an attempt at limiting crowds at certain times. You can come back later in the day if anything extra needs doing without making another appointment.
All parts of Japan use one website for the booking, so here's a guide to it.
First of all, the one website bit isn't strictly true. There's one for regular vehicles, and one for kei (yellow-plate) cars. Step one: pick the right one.
- On the front page, click "予約申込"
- On the next page, click "継続検査予約"
- You'll then be faced with a map of Japan. You will need to know your specific location, or the kanji of your prefecture, region, city etc.
- You may have several options in your area, and will need to choose which one you want. Google translate should work on this page.
- You will then be shown a list of dates and times during the following 2 week period. Days/times with a "O" mark are open for booking. "X" is fully booked.
- Lastly, you'll be asked for your vehicle registration "車両番号", licence number "暗証番号", email "メールアドレス", and confirmation of your email "メールアドレス(確認用)".
- The last screen is just a confirmation of your information. Click "next" and registration is complete.
- Click "新規アカウント登録" on the homepage to create an account.
- Google translate works for the next page, and it's simple enough anyway. Select "一般ユーザ" to say that you're a normal person, not a company. Then enter your last name, first name, skip "車検代行事業者名", phone number, email, email again, password (4-20 alphanumeric characters), password again and click the blue button to continue. Then the big yellow button on the next page.
- You'll be given an ID number which you can now use to log in back on the front page (click ログイン)
- Under メニュ click the first option. You'll need to know the kanji for your region, prefecture and city. The first dropdown box is region (not prefecture) of Japan. The second is various options within that area. Selecting one of the latter will bring up a list of options. Select "新規検査／予備検査" for new inspection.
- Below is the type of vehicle. Presuming you have a regular car, choose the first option to the left "普通車"
- You will then be shown a list of dates and times during the following 10 day period. Days/times with a "O" mark are open for booking. "X" is fully booked.
- Clicking a date/time will take you to a page confirming your details and asking for your address, and some car information. All this information can be found on your Shaken Certificate, which should be in your glovebox or where ever you keep it. Match up the kanji for a fun game! ....
- After that, confirm and you're done.