PayPay let people link an outside credit card and pay through the app. Every one of those payments came with a card network fee, and with 65M+ users that fee added up fast. Leadership set a date to turn it off. My job was to figure out how, without losing the people who used it.
I started by talking to users who paid with a linked card. Most weren’t loyal to PayPay. They used it because it’s accepted almost everywhere in Japan, while their card earned them miles and rewards. Removing card payments meant removing their reason to open the app. So the real question became: how do people keep their rewards without the card network?
The obvious fix was a top-up: charge the card, then pay from the balance. But legal flagged it. In Japan, a new stored balance counts as e-money, which needed a license we couldn’t get in time.
Vouchers don’t have that problem, because they can’t be transferred. So I proposed Credit Card Vouchers: buy a voucher with your card, keep your rewards, and pay as usual. No new license, no lost users, and engineering could reuse PayPay’s existing voucher system. It was approved quickly.
Engineering wanted to switch it off on a set date. But support data showed that surprise errors at checkout make people retry, lose trust, and feel embarrassed at the register. So I proposed a gentler path: a notice before the date, then a guided first voucher purchase. Engineering agreed.
These users had paid by card for months, some for years. The design had to teach a new habit without pushing them to another payment app.
I used CTR data to place the notice where people actually look: the payment flow and the receipt screen. I also caught a gap. People adding a card for the first time would skip both, so the notice went there too.
The hardest question was the purchase screen. Should it feel like buying a product with fixed amounts, or like a top-up where you type a number? I explored three directions: the existing gift voucher pattern, a top-up style input, and a scroll-based amount picker. Instead of deciding by opinion, I ran a bilingual survey and tested the three prototypes with 8 users. The top-up pattern won. People already knew how it worked, and that mattered more than being technically accurate. As one tester put it, “I don’t like having fixed amounts. I want to decide how much I put in myself.”
Fix, don't block
Straight back to paying
In a design review, our CEO asked to use the purchase page to promote PayPay’s own credit card. I understood the goal, but an ad there would add friction right where drop-off risk was highest. I mapped the full journey and showed a better moment: the sunset notice, when users are already deciding what to do about their card. On the purchase page, the PayPay Card option became more visible in the payment method list instead. The CEO approved it.
The feature is live for all card users. So far, about 30% of them have moved to vouchers, and I’m still tracking the data. The main signals are the voucher purchase success rate and the payment success rate. Support inquiries are the early warning: a jump there points to friction before it shows up anywhere else. What we learn will shape the next round of changes.
I set up a design QA process and a handoff kit to go with it: markers for spacing, elements and tap areas, numbered notes, and a link to each ticket. Other designers picked it up, and it became the team standard.
In a project full of legal rules, late surprises are expensive, and design absorbs most of the cost. Now I bring legal and business in much earlier. Quick research still pays off too: a survey and 8 tests moved a big decision from opinion to evidence, and gave me a clear reason to point to in every review after.
