Evidence of relationship

I will be going to Japan in a few months to marry my Japanese girlfriend. I met her on Japan Guide near the start of this year. Currently, we have known each other for a total of 6 months. Out of these 6 lovely months, I have known her for 3 of them in person. I visited her in Japan via a 90 day tourist visa (I stayed the entire 90 days). I plan on applying for a spouse visa once we are married, because she has recently been offered a good job and I see no reason to leave it behind.

I need some clarification on what kind of proof I need to submit in order to prove our loving relationship is indeed genuine once we are married and I apply for a spouse visa. We have photos of us together, chat logs (we chat every day), regular emails and phone/keitai emails from the phone I had when I was staying in Japan. Needless to say, my passport also has the arrival and departure date stamps during my 90 day stay in Japan.

How many pictures of us together do I need? How does sending chat logs work? Do I need to bring them all with me to immigration on a laptop or USB drive, or can I just take screen shots (print screen in Windows) of bits and pieces? How about web emails? Can I just take screen shots of that too? As for the phone/keitai emails, I still have them on my J-phone... so bringing that little device would be no problem or inconvenience. However, I would rather not print out 100 pages of chat logs and emails if a few screens shots showing different conversations and dates will suffice. Replies from people who have been in a similar situation and obtained a spouse visa successfully is greatly anticipated and appreciated.

If it is any consolidation, her family (mom, dad, brother and sister) love me to death. They definitely approve of our relationship and future marriage. Her mom and dad are more than willing to write letters or even sponsor our visa if needed.

a picture or two (both of you together, with date printed if possible) before marriage to show that you've known each other for quite awhile, also maybe include your wedding invitation card/picture as well..

Also make sure you have all the correct documents to apply before you go to immigration. Proof of an existing relationship is not immediately required, but you will probably be asked to submit some at a later date and maybe have an interview as well since you have only known each other for a short time and will only recently be married when you apply.

And just to clarify (to avoid the mess that's going on on the "problems with immigration" thread), you will be applying for a "change of status of residency", not a spouse visa. Its a different form and different documents are required. It would be best to have someone call the local immigration office where you will apply to find out exactly what documents are needed.

I think all of the immigration offices send the same application to a main office to be evaluated. You will get an application packet you have to fill out and part of that is proof of existing relationship. You can't bring your USB and computer, etc because they send the paper application off to immigration offices to be checked there. It can take a couple months, but they will put a stamp in your passport so you can stay past your tourist visa while you are waiting. They expect a detailed chronological history of your relationship; ie, how and where we met, how we are maintaining the relationship, we chat XXX, we have been in contact and spent 3 months together, I have traveled to Japan to meet her family, last spring we went together to my country,etc, etc.
I wrote a one page typed history for my application, and then just pasted a bunch of pics over the last couple years of us together in photoshop and printed it up on another page, us in my country, us in Japan, his family and my family in pics with us, holidays, etc. There will be instructions in English and Japanese, if you are concerned ask the immigration officer at your application office, he will give you the best advice on what they need.
I don't know if they are tougher on long-distance or shorter term relationships, but the real reason for checking everything is to make sure it is not a fraudulent marriage, so don't worry if you are truly in love. At the worst, if they suspect anything or don't have enough information (remember, they are just looking at a piece of paper you filled out, so be specific!), you will get an interview to explain the situation. They are not there to try to ruin people's relationships, but sometimes it can be troublesome to get the visa because they do have so many illegal marriages they are looking out to catch.