Hello and welcome to SR. Well done on making the decision to reduce your alcohol consumption. Are your long term plans for sobriety? There are many ways that you can deal with your addiction, but as has already been said, the first step may be to tell your doctor, who can point in you the right direction. I don't know anything about support for alcohol addiction in Japan, but they may have teams available to support you detoxing, to discuss through plans of quitting, and to generally talk to you about giving up alcohol and there may also be support groups in your area where you can meet other people with the same issue.
About the anxiety - the first thing I will say is that alcohol does make this SO MUCH worse. We feel as though it helps when we drink, and I suppose to some extent it does, but when not drunk, our anxiety is worse than ever. The feelings we have after drinking (I don't know about you but I feel shame, guilt, embarrassment) really exaggerates our anxiety and makes it worse. At first you may feel as though your anxiety is worse but over time it will get much better if you are sober.
Stick around on SR - there is much knowledge and experience on these boards and should you ever need advice there will be someone here who can help you.