Anyone who gets into cards notices it straight away: the same set exists in Japanese and in Italian, the price is different and the pack holds a different number of cards. The question is always the same — which one is worth buying? The answer changes a lot depending on whether you want to play or to collect.
Fewer cards, but also less money
A Japanese pack typically holds 5 or 7 cards, against the 10-11 of a western pack. It sounds like a worse deal, but the price drops in proportion: with us a Mega Brave pack of 5 cards is under five euros. The real maths is about cost per pack opened, not number of cards: if what you care about is the feeling of opening and the hunt for the chase card, the same budget buys you far more Japanese packs.
They come out first
Japan is the starting market: sets land there first and are only later adapted for the West, often reshuffling two Japanese sets into a single international expansion. That means buying Japanese lets you see the new cards months earlier — and it is also why certain cards only exist in Japanese for quite a while.
Print quality
Among collectors it is widely held that Japanese printing is on average more careful: more consistent centring and stiffer card stock. It is one reason Japanese cards are often preferred for grading, the professional assessment of condition. It is not a guarantee — badly centred cards come out of Japan too — but it is a real trend.
Careful: for Yu-Gi-Oh! it is not the same game
This is the most important difference, and beginners often do not know it. Yu-Gi-Oh! exists in two separate versions: the OCG, the Japanese and Asian version, and the TCG, the western version played in Italy. They are not different editions of the same game: they have different card pools, different banlists and different releases. A card can be extremely strong in the OCG and not exist yet in the TCG, or be banned on one side and legal on the other.
So a product like the Secret Shiny Box or the Secret Utility Box is wonderful to collect and to open, but the cards that come out of it cannot be taken to an Italian tournament. If you play in store, look for TCG products in Italian or English.
For the other games the distinction is not that sharp, but the point stands: before buying Japanese to play, check the rules of the event you are entering, because the accepted language varies from tournament to tournament and from game to game.
So when is Japanese worth it?
It is worth it if you open for the joy of opening, if you collect, if you care about alternative artwork versions, or if you want the new cards before they reach us. Single packs are the cheapest way to try: Mega Symphonia for the new MEGA era of the Pokémon TCG, OP-08 Two Legends for One Piece, FB09 Dual Evolution for Dragon Ball Fusion World.
Italian is worth it if you play in tournaments, if you are learning and want to read effects in your own language, or if you are buying a gift: a collection in your own language is simply more usable by whoever receives it.
You will find all the packs and boxes, Japanese and Italian, in Trading Cards.