What are Japanese phone cards?

On December 23, 1982, NTT, then Japan's national telephone corporation, launched the phone card: a magnetic prepaid card for public telephones. The problem it solved was small and universal. Payphones took coins and returned no change, so a card that held call credit in advance, and spent it down as you talked, replaced the pocketful of coins entirely.

The card held its credit in units, deducted one unit at a time as a call ran. As the units drained, the payphone punched small holes into the card itself, so the remaining balance could be read at a glance, no machine required. Within a few years the green card payphone stood everywhere in Japan, and the card was issued in the hundreds of millions: at the peak, fiscal 1995, over 400 million cards were issued in a single year.

Then the card escaped its job. A phone card is a flat, pocket-sized printed surface, and NTT's custom printing program would put almost any design on one. Companies, railways, festivals, films and anime productions commissioned their own. The prepaid card became a tiny poster that lived in a wallet, and people started keeping them for the picture long after the last unit was spent.