Methodology

How we collect and verify the data.

Every figure on this site comes from a third-party source we link to. We do not generate prices, set them, or modify them — we aggregate, average, and present.

Card metadata

• Pokemon TCG: Card lists, illustrators, and rarity codes are sourced from the public pokemontcg.io v2 API and cross-referenced with the official Pokemon-Card.com site. Card images are loaded directly from the official Pokemon TCG image CDN.
• One Piece Card Game: Both Japanese and English card data come from onepiece-cardgame.com (operated by Bandai). Card images are loaded directly from the official server.
• Dragon Ball Fusion World: Card data and images come from dbs-cardgame.com/fw/ (operated by Bandai).

PSA Population

PSA Pop counts (PSA 10, 9, 8, Auth, total) are sourced from the official PSA Population Report at psacard.com/pop. Counts are refreshed weekly. Mapping each Japanese-language card to its PSA listing is done manually for accuracy and audited per set. This data is being added — see card pages for "indexing" status until each set is mapped.

Marketplace prices

• eBay PSA 10 sold (USD): 30-day rolling average of "Sold" listings on ebay.com matching the card's English name + set code + "PSA 10 Japanese". Refreshed weekly.
• eBay PSA 9 sold (USD): Same query with PSA 9. Useful as a floor reference.
• Mercari raw lowest (JPY): Lowest 3 active listings on jp.mercari.com matching the Japanese card name + set code. Refreshed weekly. Note: Mercari data is gathered respecting the platform's rate limits and is shown as a market estimate, not an official quote.

What we do not do

• We do not buy or sell cards on this site (yet — that's a Phase 2 plan, separate from the editorial layer).
• We do not accept paid listings or sponsored card features.
• We do not manually adjust prices in either direction.

Refresh cadence

All marketplace and PSA data is refreshed once per week (Monday 03:00 JST). Card metadata is refreshed when a new set is released. The "Last updated" timestamp on each card page reflects the marketplace data refresh, not the metadata.

Known limitations

• eBay sold sample sizes can be small for niche cards. We display sample size next to every average.
• Mercari listing prices are asking prices, not transaction prices. Treat them as a ceiling for raw cards.
• Currency conversion between JPY and USD uses the most recent FX rate at refresh time, not the per-transaction rate.
• We use English card names and translations from the official English releases where available. For Japan-only cards, names use the Japanese print's English equivalent or a romaji approximation.