Can you bring a knife on a plane?

The rule for knives comes from the Civil Aviation Bureau's list of restricted items and is the same on domestic and international flights.

Japan's list files flick knives and daggers with swords: checked baggage only. It also warns that under the Firearms and Swords Control Act and other laws some blades cannot be possessed in Japan at all.

Almost every list refuses a knife in the cabin and accepts it in checked baggage. The lists differ on blade length, table knives and knives that are illegal to carry.

Why the hold takes what the cabin refuses

Narita Airport's FAQ explains the split. Carry-on baggage is inspected for anything that can be used as a weapon, to prevent hijacking. Checked baggage is inspected for goods prohibited from transport, such as explosives. That is why, the airport says, knives are prohibited in carry-on baggage as possible weapons but permitted in checked baggage.

No blade length in Japan's knife row

The European Commission's list bans knives with blades of more than 6 cm from cabin baggage, and South Korea applies the same 6cm line to knives that are not folding or multi-purpose. Japan's knife row has no length in it. Every knife starts as not allowed in the cabin; the way out is a tip that is not sharp plus the judgment that it cannot serve as a weapon.

Knives the Japanese list answers one by one

Around the main row the list answers for specific knives. An oyster knife cannot be carried on because its shape looks threatening at a glance. A paper knife can, when the tip is not sharp and it is judged not to be a weapon. A scalpel cannot, medical ones included. The switchblade is listed with swords and is not allowed in the cabin.

Table knives and cutlery

Japan's example of a knife that can pass is a butter knife. The TSA excepts knives with rounded blades and blunt edges without serration or teeth, and plastic cutlery. Australia's Home Affairs is stricter with tableware: metal cutlery is on its prohibited list and a plastic cutlery knife is on the allowed one. South Korea lets in-flight meal knives through only when they belong to the airline.

Knives that cannot be carried at all

The preface to Japan's list warns that some items cannot be possessed in the first place under the Firearms and Swords Possession Control Law and other laws. Hong Kong applies that idea to travellers changing planes: a gravity knife, or any knife whose blade is exposed by a spring or other mechanical device, is illegal to carry there in carry-on or checked baggage, transit passengers included.

Knives are allowed in carry-on under conditions in the European Union and South Korea.

Each row comes from that authority's own page. Airlines can be stricter, and the screening officer has the final say.

What to do

Move knives to the bag you check in before you reach security. Narita Airport states that anything given up at the checkpoint is discarded and cannot be returned.

If it gets on board

Taking an item that is restricted from the cabin onto an aircraft is punishable under Japan's Civil Aeronautics Act: up to 2 years' imprisonment or a fine of up to 1,000,000 yen.

Where to buy

Kitchen knife shops, for example in Kappabashi in Tokyo and Sakai in Osaka. Have it wrapped and put it in your checked bag.