Japaneselaw about knife and sword

"Don't have knives or swords below."

・Katana over 15cm (6 inch)
・Sword over 15cm (6 inch)
・Spear over 15cm (6 inch)
・Partisan over 15cm (6 inch)
・Dagger
・Automatic open knife

Length of knives and swords ware meajured from A point to B point.
In case of Katana, straight line from A to B is not on the blade. So it's one of defines of Katana.

In case of drop pointed knife, straight line from A to B is in the blade ,so it's not Katana.

Length of knives is defined as follows.

In Japan, Knives have to be short as 25 cm(10 inch) by judicial precedent.

If your knife length is over 15 cm, cut like saw .

"Carring knife"

You have to not carring knife over 6 cm (2.4 inch) in city.