Disclaimer: I do not claim any rights to Get Backers anime/manga - nor to the characters within the series. I simply write, and occassionally bastardize them in prose. Enjoy.
A man's wallet is a very personal thing. It's a private thing - like a toothbrush, or underwear - peeking into it gives insight into the things that particular man finds most important.
Compared to some, Mido Ban's wallet is a barren wasteland; containing that which is necessary for day to day life and very few "personal effects"...but then, Mido Ban isn't really the sort of man to carry around more than is absolutely necessary.
The well-worn leather of his wallet is slightly cracked, but in good shape otherwise; the long pocket used to hold folding money and paper slips holds an old gum wrapper, a little over six hundred yen, and a condom (one never knows, after all). His driver's license, a single credit card, and a fairly crushed packet of matches make up the other contents of Ban's wallet.
Mido Ban carries two photographs as well. Both are dog-eared and tattered; one is a group shot containing a younger Ban, a serious looking older boy, and a short-haired girl with tanned skin. The other photograph is more recent, but worse for the wear: a smiling blond with short spikey hair grins past the camera, his laughter frozen in time forever.