For foreigners（Sorry, English only）

Do you have skin problems?

If you have had a similar condition in the past and know how to treat it

You may be able to treat it with over-the-counter medicines. Some corticosteroid creams are available, including betamethasone valerate cream. Anti-fungal creams are also available. You can buy these from your local pharmacy. EC websites may be helpful. However, if the symptoms don’t improve within 1 to 2 weeks, you should see a dermatologist.
Another piece of advice is that over-the-counter medicines in Japan often contain topical anaesthetics, antihistamines, etc. These can cause a rash.
If you have a severe, prolonged or unknown condition

Consult a dermatologist. Your Japanese friends or “Kumamoto Support Center for Foreign Residents” can be a good help.
You can also find a local dermatologist on the Medical Information net (NAVII). It may feel like a hassle to find the clinic you need. Be patient. First, change the language to English. Then select “Search by prefecture-specific function” to “Kumamoto”. Enter “dermatology” in “Search by keyword”. Press the upper button “Display map” to easily display your nearist clinic. Confirm the “Foreign-language support available” icon.
When going to the hospital

As you know, many Japanese are not accustomed to speaking English. Even if a dermatologist is fluent in English, nurses and receptionists may freeze up when they realize that the patient does not speak Japanese. The use of a translation app is strongly recommended. If you go with a Japanese friend, you can avoid the nervousness of the staff and minimize the effort on our part.
You should also be prepared with information from your health insurance company. Staff at Japanese hospitals are often not familiar with dealing with medical insurance for foreigners, so it is recommended that you contact the “Kumamoto Support Center for Foreign Residents” to obtain the necessary information.

Translated with DeepL.com (free version) : )