This is exactly the kind of decision where "Rakuten gives more points, so it's cheaper" quietly costs you money — because points aren't cash, and higher list prices hide the trade. Mio doesn't care which app you like. Here's the math.
Sticker price is not what you pay. The number that matters is the effective price — sticker minus the points you'll actually use:
Points only count if you'll spend them before they expire. A ¥10,000 item that "gives back ¥1,500 in points" is only ¥8,500 if those points get used on something you'd have bought anyway. Otherwise it's still ¥10,000.
| Store | Strength | Points (typical) |
|---|---|---|
| Amazon Japan | Lowest sticker, English UI, fast Prime delivery | Low / occasional |
| Rakuten | Point stacking (SPU + campaign days) if you use their card/mobile | High (but variable) |
| Yodobashi | Electronics, free shipping, reliable stock | ~10% flat |
Amazon wins on simplicity and honesty of price. Rakuten wins on total return — but only inside its own economy. Yodobashi is the quiet middle: steady 10% back plus free shipping makes it a strong default for gadgets.
| Store | Sticker | Points back | Effective price |
|---|---|---|---|
| Amazon Japan | ¥9,800 | ¥100 | ¥9,700 |
| Rakuten (normal day) | ¥10,500 | ¥300 | ¥10,200 |
| Rakuten (SPU + campaign) | ¥10,500 | ¥1,600 | ¥8,900 |
| Yodobashi | ¥10,000 | ¥1,000 | ¥9,000 |
Read it carefully: on a normal day Amazon is cheapest. On a Rakuten campaign day with full SPU, Rakuten flips to cheapest — but that ¥1,600 is only real if you'll spend those points. Yodobashi sits reliably around 10% back with no campaign gymnastics.
Two ways points quietly cost you money:
1. Expiry. Many points (especially campaign/limited points) expire — sometimes in weeks. Points you never spend are worth exactly ¥0, which means you paid the full sticker price after all.
2. Buying more to earn more. The classic "point trap": you add a ¥3,000 item you didn't need to hit a campaign threshold and earn ¥900 in points. You didn't save ¥900 — you spent an extra ¥2,100. Points can only reduce the cost of things you were going to buy anyway.
Not in the Rakuten economy (no Rakuten card/mobile) → Amazon for simplicity and the lowest honest price. Buying electronics → Yodobashi for steady 10% + free shipping. Deep in the Rakuten ecosystem and it's a campaign day → Rakuten can genuinely win — but only on items you already planned to buy, and only if you'll spend the points before they expire. Compare the effective price, never the sticker.