Checked against UN INCB controlled substance lists and Japan rules.
Japan classifies methylphenidate as a psychotropic, not a stimulant. The Narcotics Control Department lists it among the substances that need no import permission at all, alongside zolpidem and alprazolam. What still applies is the ordinary ceiling on prescription medicines: up to one month's supply without an import certificate. Adderall is the opposite case under Japanese law, and the two are constantly confused.
Concerta contains a substance on the UN International Narcotics Control Board lists. Most countries that signed the UN drug conventions expect you to carry a prescription and declare it.
Check the permitted quantity and formulation before you pack. Carry the prescription and original packaging.
Official source for Japan: www.mhlw.go.jp
Original labelled packaging, the prescription, and a letter naming the active ingredient in generic form — control lists are written in generic names, not brands. What the letter must say. And the destination’s own procedure.
Not legal or medical advice. Rules change and depend on dose, form and quantity. Always confirm with the Japan embassy or health authority before you fly. We never tell you a medicine is "safe" to carry.