3.2K WORDS · KOHTA KOUCHI
What shipping a new currency taught me about product
Working as a PdM on a Mercoin launch — where the hardest design problem was trust, not UI.
At Mercari's FinTech arm, Mercoin, I owned the launch flow for a new currency — how it was explained to customers, the landing page design and build, and the release itself. In FinTech the interface is the easy part; the product is trust.
Every screen is a small contract. A number in the wrong place, a word that overpromises, a flow that hides a fee — each one quietly spends credibility you can't easily earn back. So the work was less 'make it pretty' and more 'make every claim true and obvious'.
The lesson stuck: in money products, clarity is the feature. If a user has to wonder what just happened, you've already shipped a bug.