How to read a Japanese set code: OP-17, SV2a, M6a and the rest

The code is the name

Ask a collector what they are opening and they will not say “the Kingdoms of Intrigue booster”. They will say OP-04. The set name changes between Japanese and English, and it changes again between one shop’s listing and the next; the code does not. It is printed on the box, it opens every card number in the set, and it is the one string that means exactly one product.

That is why it is worth two minutes to learn how each one is built.

One Piece: the letters before the number

The One Piece Card Game keeps it simple. The letters say which kind of product it is, the two digits say which one in that run. OP-nn are the main booster packs — OP-01 Romance Dawn came first, in July 2022, and the run has been continuous since. EB-nn are Extra Boosters, smaller sets that sit between the main numbers. ST-nn are Starter Decks, sold ready to play. PRB-nn are Premium Boosters.

Inside the set the card number drops the hyphen and adds the card’s own three digits. OP01-121 is card 121 of OP-01, the Yamato Secret Rare. A parallel print does not get a number of its own — it shares the number of the card it is a version of, which is why one number can exist in three different frames.

Pokémon: era, number, and sometimes a letter

A Japanese Pokémon code reads left to right in three parts. The first is the era: S is the Sword & Shield era, SV is Scarlet & Violet, M is the MEGA era that began in 2025. The letter changes when the generation does. The second is the number, counting that era’s main Expansion Packs in order: SV3, SV6, SV8, SV10. The third, when there is one, is a letter — and it does one of two jobs.

A letter that pairs two sets. When two sets share a number and differ only in the final letter, they are two halves of one release and they went on sale the same day: SV1s Scarlet ex and SV1v Violet ex (20 January 2023), SV2d Clay Burst and SV2p Snow Hazard (14 April 2023), SV4k Ancient Roar and SV4m Future Flash (27 October 2023), SV5k Wild Force and SV5m Cyber Judge (26 January 2024), SV11B Black Bolt and SV11W White Flare (6 June 2025), and M1L Mega Brave and M1S Mega Symphonia (1 August 2025). Buy one and you have half the set.

A trailing “a”. It marks a supplementary set that sits between two main numbers instead of replacing one. Those are the Enhanced Expansion Packs and the High Class Packs: SV2a Pokémon Card 151, SV4a Shiny Treasure ex, SV8a Terastal Festival ex, S12a VSTAR Universe, M2a Mega Dream ex. They are usually smaller than a main set and usually heavier on chase cards.

One honest note: the publishers do not print a key to the individual letters. Treat the whole code as one label — that is how it works in practice, and it is what every listing, tournament report and price guide uses.

What to do with it

Type it. The code is the fastest way into anything: put OP-17 or M6a into the search box in the magazine and you get the set file and the box in the shop at once. It works the other way too — if you are holding a card and want to know where it came from, read the first half of its number.