Medicine restrictions

Hi there,
I am packing some medication for the upcoming trip to Japan and was wondering about possible restrictions.

I know that for instance, Pseudoephedrine and other drug related medicine is prohibited.

I will only bring some painkillers (Paracetamol, Ibuprofen), antihistamin (Loratadine), drops for removing plug of vax (if any), wound treating items (plasters, dressings, chlorhexidine, etc).

Should any of these be written in the customs declarance form by the way?

You are correct that you should not carry any pseudoephedrine or any opiods, etc.
Paracetamol is just another name for acetaminophen or tylenol. No problem with that. But if you are carrying any prescription medicines you absolutely should carry your prescription with you and if you really want to be safe, a letter from your doctor that you need it.
You don't need to declare any such items on your customs form. In fact, it is fairly possible you won't get your bags searched and you'll just be questioned - so if you want to save yourself from unneeded scrutiny, don't volunteer any info either. They'll ask you if you are carrying any narcotics, recreational drugs and so on, and you are not, right?

Not sure about prescription info but they put a tag on the medication box with my name and birthdate on it for prescription drugs. The text is unfortunately not in English though. Not sure if I would still need letter from the doctor.