Studio Ghibli is a fantastic place to visit while you're in Japan, but figuring out how to buy the tickets can be pretty infuriating. From the United States you can order them from travel agents, but you'll end up paying a lot more. If you're in Japan (or have a friend in Japan) they can buy them on the Loppi machine at Lawson, but it's not the most simple or intuitive process, and it can't be done in English.
To make it more frustrating, Studio Ghibli has a link on it's website showing instructions in English on how to buy the tickets, except that many of the steps are missing. If you follow their guide, you won't be able to finish if you can't read Japanese, and even if you can it may still be a struggle.
My sister is coming to visit soon, so John and I bought tickets and I took pictures of each step along the way to fill in all the information that is missing. If you follow all these steps, you should be able to get the tickets you want, assuming the tickets aren't sold out.
That's the other thing - tickets are limited and sell out incredibly quickly. Currently, tickets go on sale at 10:00 am on the 10th of the preceding month (e.g., tickets for April go on sale March 10th). I bought tickets 45 minutes after they had gone on sale, and my first choice of time (noon) was already sold out and I had to go with my second choice (2:00 pm). Granted, this was for a weekend date during cherry blossom season, so I can only imagine demand is higher than usual, but be aware that you should purchase your tickets as far in advance as possible. The last time my sister visited we tried, but failed, to get tickets because we didn't plan far enough ahead.
This is the home screen of the Loppi Machine. The green button is for Studio Ghibli tickets.
This screen shows which months tickets are available for. 月 is the kanji for month, so 3月 is March, 4月 is April, etc. Choose your preferred month.
Don't worry, this screen doesn't mean tickets are sold out. Just touch the orange button at the bottom.
Select your preferred date. Don't let their calendar display fool you, they list the week starting with Monday and ending with Sunday, rather than the Sunday-Saturday format you may be familiar with. As you can see, the museum is closed on Tuesday. (Confession: I accidentally bought tickets for Sunday when I meant to buy them for Saturday. Sigh.)
Select your preferred time. You have 30 minutes from the time your ticket states to enter the museum, so don't be late! (e.g., 12:00 pm tickets allow you to enter from 12:00 to 12:30)
Click the highlighted button to confirm your selected date and time. If you've made a mistake, use the arrow on the upper left (前に戻る) to go back a screen.
Select the number of tickets you need. The top choice is for adults, the middle choice is for children age 13-18, and the bottom choice is for children age 12 and under. After selecting the appropriate number, click the orange button.
If you see this screen it means that tickets are sold out for the date and time you have selected. Click the orange button then go back and try for a different time or date.
If you see this screen it means that the tickets you requested are available! Now it's asking you to create a point card, but you want to skip this step. Click いいえ on the left.
This screen is asking for your name.
It will not actually be printed on your tickets, only on the receipt that you take to the cashier. (In my case the clerk did not ask for identification) UPDATE: in an effort to prevent ticket scalping I've heard that Studio Ghibli is now putting names on tickets and actually checking IDs. If you need to know how to write your name in Japanese, you can use this website. You'll want to use the hiragana, not the katakana or kanji. Be sure to type a space between your first and last names by using the button on the top right of the keyboard (一字あげる). I got an error message when I didn't do that.
After you type your name in hiragana on the top line, press this button to convert it to katakana on the second line.
This screen is asking for your phone number. If you don't have a phone number you can enter your hotel's or make one up. If you make it up, enter 03-(4 digits)-(4 digits).
Again, confirm that you've selected the right date and time for your tickets and touch the orange button at the bottom.
Don't panic! Nothing is wrong, they're just confirming yet again that you really want to buy these tickets. Click はい.
Yay! You've succeeded in reserving tickets! A receipt is printing out of the machine right now. You have 30 minutes to take it to the cashier and pay for the tickets. After 30 minutes your reservation will be cancled. When you pay, they will print your Ghibli tickets out on a machine behind the counter and give them to you in an envelope.