First year of college is great. I want to be one again. I graduated from the Faculty of Law and the Faculty of Buddhism. I also wrote “I want to be a historian or archaeologist” in my elementary school graduation book. I've written something before, and I love history.
There aren't many specialized subjects in a year, so it probably won't fall into a narrow field. However, when it was 2 or 3 years, it suddenly became a specialized field, and I was confused by the names of people, place names, systems, and historical materials that I had never heard or seen. Because it's a time like this, I think it's a good idea to try a book specialized in national history.
However, even if you open a thick research paper, you may be stuck if you don't have sufficient basic knowledge. Even if you study national history, I think the times you're interested in and the fields you're interested in are pretty much fixed. Why don't you read a history book about a person who became a key person in your favorite era?
What I just came up with is a series of people from Yoshikawa Kobunkan. For example, if you are interested in the shogunate system in early modern political history, read “Tokugawa Iemitsu,” “Hoshina Masayuki,” and “Matsudaira Nobutsuna.” If you are interested in the literary history of the late Heian period, read “Saigyo” and “Fujiwara Sadaike.” I think reading books like this will deepen my knowledge about systems, human relationships, and incidents through people. If you do that, even if you start reading historical materials in 2 or 3 years, I think it's pretty easy to put in.
Also, please note that, depending on the book, many character series are mainly described based on old theories. I think there are many things that remain the same content that has been denied in the latest theories. I'm a monk of the Soto sect. If I ask my friend who is an expert on Zen history, it seems that “Dogen” also has quite a few points that need to be rewritten.
From the point of view of people who have finished college, 4 years of college seem long and short. But it's a precious time where you can study carefully. I hope you have a meaningful college life.
