If you get sick in Japan... but not enough to go to the doctor
Well, it can be a cold, a hangover, jetlag, ...
There are plenty of pharmacies in Japan. The thing is, they do not always look like pharmacy. They usually sell a lot of different things that you do not expect to find in a pharmacy.
Such as beauty product like shampoos, shavers, hair dying products. They have stockings and many other things you might need. They also have a large panel of diet products, from herbal teas to substitution food and proteins for body builder wannabees. They have home and laundry cleaning products (they also have travel size packages and this is very handy). Pet litters and food.
They have many supplement: if you lack energy (there are many kind of drinks but I do not recommend them), if you have a hangover: they have many drinks that will help reconcile your liver with your evening, amino acids for runners... By the way, amino acids are also good for hangovers.
They even have drugs and medicine! The best thing to do is to tell the pharmacist what you have: there are medicine to get rid of cold symptoms, usual pain killers, ...