Amazon Prime membership
Prime is currently ¥600 a month or ¥5,900 a year, so paying yearly saves you ¥1,300. Students at a university, graduate school, junior college, or vocational school can get Prime Student for ¥300 a month or ¥2,950 a year, with the first 6 months free.
The most practical perk is shipping. If you're not a member, orders shipped by Amazon under ¥3,500 come with a ¥460 shipping fee, or ¥500 to Hokkaido, Kyushu, and Okinawa, and expedited (お急ぎ便) and same-day (当日お急ぎ便) delivery cost extra on top of that. Members get all of it free. Two small orders of everyday odds and ends under ¥3,500 a month and the fee pays for itself.
Prime Video is included too, but it started showing ads in April 2025, and skipping the ads costs another ¥390 a month. The sale prices on Prime Day in July and Prime Big Deal Days (プライム感謝祭) in October are members-only too.
If you don't buy much normally and only place orders during big sales, signing up for a month before the sale is enough. After you join, turn off auto-renewal on the membership page.