sCrUM_MASTER

This is the real answer, most people don't care but they like banding together and having someone else be the "other group"

You'll be fine, both in Japan and back home I've lent people my card and vice versa, the only time I ever had someone look at the name was buying something from Bic Camera. It was over 5k yen so I wanted to get the tax discount, and they looked at my passport and compared the name on my debit card.