My friend asked about this so I thought I would put it on here where everybody can see it.
This is some info about bringing drugs to Japan and the yakkan shoumei.

You may bring up to one month's supply of prescription drugs into Japan, and up to two month's supply of non-prescription drugs without completing any paperwork.
This same rule applies to mailing prescription and/or non-prescription drugs.
However, if you wish to take more than a month supply of prescription drugs or more than two months supply of non-prescription drugs to Japan, you must obtain a "Yakkan Shoumei," an importation certificate.

1. What to submit when applying for the certificate
1) Import Report of Medication (2 identical, original sheets. Copy is not accepted.)
2) Declaration (1 sheet)
3) Explanation of the Product (1 sheet for each product)
4) Either a) a copy of Prescription or b) direction for medicines with doctor's signature, by which the Pharmaceutical Inspector can clearly confirm that the name and the quantity of each medicine is only for his/her own personal use.
5) Copy of Airline Ticket or Official Flight Itinerary
6) Self-addressed Japanese stamped Return Envelope (you may obtain an International Reply Coupon* from the Post Office in lieu of Japanese Stamps.) A Return Envelope needs to be at least 23.5 cm by 12 cm.

Go to this page for more info and for the forms:
http://www.mhlw.go.jp/english/policy/health-medical/pharmaceuticals/01.html

Here are some that are not allowed (but there are more! )

When in doubt.. call your local Japanese consulate and ask them about your drugs before coming.


Tylenol Cold
Nyquil
Nyquil Liquicaps
Actifed
Sudafed
Advil Cold & Sinus
Dristan Cold ("No Drowsiness"
Dristan Sinus
Drixoral Sinus
Vicks Inhaler
Lomotil