A dissertation is about asking a question, analyzing it, and solving it~! What kind of questions can be asked about alcohol?

If you are not writing a thesis on the topic of the way Japanese people contact other people when they drink, then make the topic;

Japanese people's way of drinking and paying for it

To analyze this aspect, you need to look at a lot of information, such as the web pages written by Japanese people themselves, and the various inner thoughts they have when they drink, etc.

And then analyze the thoughts of the Japanese people, their habits and conflicts.

Then analyze the Japanese people's thoughts, habits, and conflicts.

When you look at such information, it is good to find it in the ancient song website.

Take "お酒の席で"""饮み会""酔い酒 "etc as keywords and you will find it.