Business cards are used frequently in Japanese business settings, so running out at the wrong moment can feel a little awkward. But not having a card does not automatically ruin a meeting or amount to a serious breach of etiquette.
If it happens, simply apologize briefly and introduce yourself verbally. You can say that you have run out of business cards, then give your company name, department, and name.
If the other person offers you their card, you can still accept it normally even though you cannot give one in return. There is no need to refuse their card just because you have run out of your own. You can receive their contact information, give your own details verbally, and provide anything missing later by email.
Business etiquette guides often say that you should make sure you carry enough cards. That is sensible advice. In practice, though, running out once is unlikely to damage someone’s impression of you very much on its own.
If the person apologizes and introduces themselves properly, it is more likely to be treated as a simple mistake: sometimes people run out of cards.
It becomes a little different if someone repeatedly misjudges how many cards they need for important visits, or regularly runs out halfway through meetings despite working in a role where business cards are used constantly. At that point, the concern is less about the card itself and more about how well prepared the person is for work.
There is no special substitute ritual when you run out of business cards. Apologize briefly, introduce yourself, and provide any missing information afterward. That is usually enough.
