The interview was at the 2018 Tokyo Summer Career Forum.
There was a preliminary interview at the booth in the forum that was about 15 minutes, you were given a card that has a chart on the back where interview times and results would be written following every interview. Deloitte also had its own special interview area with about a dozen rooms. You can either schedule a preliminary interview by applying online prior to the event, of your can walk-in to the booth and schedule one.
Once you finish the preliminary interview, you were given your first interview time slot.
You were then taken into a room with other candidates and instructed on how you will be asked to analyze a case and make some suggestions to your hypothetical clients. Once everyone entered, you were given a three page packet of information, mostly graphs, charts, and figures to analyze in order to answer the questions posed to you on page 1 of the packet.
After that, you were sent to a room with an interviewer and you would explain your ideas. They didn't necessarily expect you to finish. For about 15 minutes, you would have to explain your ideas. The interview was entirely in Japanese, but there was a brief English component.
If that goes well, they take your card and write a remark. You then take the card to the reception and they inform you of your next interview, usually 2 hours later. If you are told that they are borrowing your card and that you should check the whiteboard outside of the special interview area to find out the results of the interview, that's their soft way of telling you it's the end of the line. They tell you that if you are successful your number will be written, but this is just their way of letting you down gently.
The second interview started immediately with the interviewer and the case right in fron of you as you enter the room. I don't remember the topic, but I think it was about an electrical company. Their standards for the second interview are much higher, and that's where many people were cut, including myself.
I'm not sure what the third one was, but I assume it's more of a character interview that asks you about your interest and motivation for wanting to work at Deloitte.
Overall, the process takes one whole day, from the start of day at the convention, to its end. Around 6-8 hours because the interviews are usually spaced two hours apart. If you are interviewing with other companies, be careful with your schedule and talk with the receptions. Bring lots of food to keep your energy up. It's a fairly exhausting process.