Japan has typical customs allowances for duty-free items; see Visit Japan Customs (www.customs.go.jp) for more information.
Stimulant drugs, which include ADHD medication Adderall, are strictly prohibited in Japan. Narcotics (such as codeine) are controlled substances; in order to bring them for personal medical use you need to prepare a yakkan shōmei – an import certificate for pharmaceuticals. See the Ministry of Health, Labour & Welfare's website (www.mhlw.go.jp/english/policy/health-medical/pharmaceuticals/01.html) for more details or contact the Tokyo office directly at firstname.lastname@example.org.
Visas are generally not required for stays of up to 90 days.
Citizens of 68 countries/regions, including Australia, Canada, Hong Kong, Korea, New Zealand, Singapore, USA, UK and almost all European nations, will be automatically issued a tanki-taizai (temporary visitor visa) on arrival. Typically this visa is good for 90 days. For a complete list of visa-exempt countries and durations, consult www.mofa.go.jp/j_info/visit/visa/short/novisa.html#list.
Citizens of Austria, Germany, Ireland, Lichtenstein, Mexico, Switzerland and the UK are able to extend this visa once, for another 90 days. To do so, you need to apply at the Tokyo Regional Immigration Bureau before the initial visa expires.
Anyone entering Japan on a visa for longer than the standard 90 days for tourists will be issued a resident card (在留カード; zairyū kādo); these are given out at Narita or Haneda airports (show your visa to airport staff to be directed to the correct counter). The resident card works in lieu of a passport for identification and must be carried at all times.
It is difficult these days to find jobs, even English-teaching ones, that offer visa sponsorship. If you do find one, know that the sponsorship process can be a lengthy one – typically taking at least three months.
The first step is to apply for a Certificate of Eligibility, which requires handing over any number of documents (depending on the desired visa status), at your nearest Japanese immigration office. Once this certificate has been issued, you can then apply for a visa. Some companies may handle some or all of this process for you.
Given the high cost of living in Tokyo, it makes sense to secure employment and, at the very least, the Certificate of Eligibility while still in your home country.
Citizens of 20 countries/regions are eligible for working-holiday visas: Argentina, Australia, Austria, Canada, Chile, Denmark, France, Germany, Ireland, Hong Kong, Hungary, Korea, New Zealand, Norway, Poland, Portugal, Slovakia, Spain, Taiwan and the UK.
To qualify you must be between the ages of 18 and 30 (or 18 and 25 for Australians, Canadians and Koreans) with no accompanying dependants. With few exceptions, the visa is valid for one year and you must apply from a Japanese embassy or consulate abroad.
The visa is designed to enable young people to travel during their stay, and there are legal restrictions about how long and where you can work; you may also be required to show proof of adequate funds.
For more details, see www.mofa.go.jp/j_info/visit/w_holiday.