Denomination-price mismatch creates a top-up mindset

What it is

When recharge denominations (the virtual-currency amounts for ¥6 / ¥30 / ¥98 / ¥198) do not map onto item prices in whole-number ratios, players always end up with a leftover balance too small to buy the next item. That leftover creates top-up pressure: an idle balance feels wasted, topping up to the next item needs one more purchase, and actual spending exceeds original intent. The "just a little short" structure turns recharge tiers into a continuous-spending hook.

Why it happens

Top-up psychology is jointly driven by loss aversion and sunk cost. The leftover is mentally booked as "an asset already paid for but unused," and idleness produces a persistent mild loss feeling; the top-up offer reframes "spend another small amount" as activating an existing asset—the new outlay is described as "covering the difference" rather than "a new purchase," and payment resistance drops well below an independent buying decision. Deliberate denomination mismatch guarantees the leftover never disappears: non-integer ratios (recharge ¥30 for 3,000 gems while the item costs 3,280) ensure every recharge lands just short, and each "just short" triggers another recharge decision. For minors and players prone to impulsive spending, the top-up loop's real spending growth far exceeds the denomination gap itself.

Where it stops holding

Denomination-price mismatch is not always intentional—payment-channel fee structures, multi-currency rounding, and legacy pricing can all produce non-integer ratios, and the ethical judgement must separate "mismatch occurred" from "designed for mismatch." Top-up pressure also varies by population: budget-conscious players compute and refuse to top up (they write off the leftover as a recognised loss), while impulsive players bear the top-up loop—that is exactly why protective design should focus on the latter. Several markets now regulate unused virtual-currency balances—requiring refunds within a reasonable period or indefinite validity—which limits the "leftover trap's" profitability at the institutional level.

Applying it

• Set common item prices as whole-number multiples of recharge denominations so one recharge exactly covers a whole number of purchases, eliminating structural leftovers.
• When the balance cannot cover a purchase, clearly show "¥X short" and offer a direct difference-only payment (pay the gap, not another full tier).
• Verification: measure the leftover-balance distribution across player accounts and the rate of "top-up-style recharges" (recharging immediately after a purchase). After fixing denomination misalignment, the top-up rate should drop significantly; if it does not, other motivations are driving it.

Related

• Same group: W10.01.1 Virtual currency layers blur the real cost of spending · W10.01.3 Purchase prompts must not exploit frustration · W10.01.4 Balance presentation shapes spending perception
• Nearby: W10.01 In-app purchases and virtual currency · O1.02 Pricing and value perception · C3.09 Decision-making and loss aversion
• Search terms: top-up design · leftover balance · dark pattern · monetisation ethics