About

Data-driven sealed booster box research

OP Box Index tracks Japanese One Piece sealed booster boxes, active eBay listings, sold-price trends, Top 10 chase cards, NM price references and PSA population data.

The site is built for global collectors in the United States, Japan, Singapore, Malaysia, the Philippines, Thailand, Vietnam, Indonesia and other TCG markets. Southeast Asian readers: our regional price guide converts every benchmark into PHP, SGD, MYR, IDR and THB and explains the Asia English edition.

What the site measures

• Booster box active listings and sold-price trend signals.
• Top 10 chase cards for each set, with NM and PSA 10 references where available.
• Supply (listings on sale), demand (sales pace) and price-spread indicators — reference only, not buying advice.

Operating principles

• Verified lowest eBay box listings and PSA 10 active links are refreshed every day at 03:00 KST when the automated job can access eBay data.
• Broader card-price and box-market datasets are refreshed on a weekly cycle, with manual review when matching quality is uncertain.
• Data tables and set summaries are generated from versioned ledgers by documented scripts. Automation does not fill missing prices, pull rates or release dates; explanatory articles are dated again when their method or factual claims change.
• Paid Link: OP Box Index may earn a commission from qualifying purchases made through eBay links, at no extra cost to the buyer.
• We prefer showing fewer verified links over showing low-quality matches. If a PSA 10 active match is not reliable, the site may show a search link instead of a direct listing.

Where every number comes from

• Sealed box prices — eBay sold results and active listings (queried through eBay's official API), plus weekly ungraded market values. Listings from China-region sellers are excluded, including sellers that route stock through US warehouses; we maintain a hand-verified exclusion list and add to it whenever a reader or our own review flags one.
• Japanese card prices (NM) — retail listings from Yuyu-tei, one of Japan's largest single-card shops. Every price is matched to the exact printing by hand: a manga-art parallel, a stamped super parallel and a plain parallel of the same card number are treated as different cards, because they trade at prices that differ by 10x or more.
• PSA 10 prices — recent eBay sold medians where at least three variant-verified sales exist; otherwise the lowest verified active listing, clearly labeled "ask". We never blend the two.
• Grading data — PSA population via GemRate's set-level aggregation, snapshotted weekly; CGC and TAG read from each grader's own report. Japanese and English printings are recorded as separate series and never added together: they are different print runs, so a combined gem rate would describe neither. Each set page shows the cumulative graded count, PSA 10 count and gem rate for both editions, plus the change since the previous week; the same figures for every set sit side by side on the PSA population page. We publish week-over-week change only from the date we started recording it, and we do not republish historical series compiled by others.

Accuracy policy

Our core rule is simple: a blank cell beats a wrong number. When a sample is too small (fewer than three sales), when a card has multiple printings we cannot tell apart in listing titles, or when a market has no reliable data yet, we leave the field empty and say so. Corrections ship the same day we confirm them — past examples include rebuilding an entire set's NM price table after finding a parser fault, and replacing box "lowest price" links after identifying disguised China-based sellers. The full data pipeline is documented in how our market signals are calculated.

Who runs this

OP Box Index is an independent, one-operator research site based in South Korea, run by a sealed-box collector who got tired of price sites that mix languages, mix card variants and hide their sources. The site launched in June 2026. It has no relationship with Bandai, PSA, eBay (beyond the standard affiliate program) or any card shop, and no one can pay to change a number on this site.

Update cadence

• Box lowest-listing links and PSA 10 listing links: daily (automated).
• Weekly box market series and PSA population snapshots (Japanese and English recorded separately): weekly, every Monday.
• Japanese NM card prices: weekly-to-biweekly, with immediate manual re-checks when a price looks anomalous.
• Data reports (see Articles): published when the data says something worth writing down.

Contact & corrections

Spotted a wrong price, a mismatched card variant, or a listing from an excluded seller? Email gsa@whatsong.kr — verified corrections are applied within a day and noted in the site's change history.

All information is for research only. It is not financial or investment advice.