She likes Japanese history and is very familiar with the Tokugawa Shogunate.
This is one of those words that makes more sense when you look at the reading. The "Virtue River" isn't some virtuous river, it's in fact the Tokugawa family name, also known as the Tokugawa Shogun. They ran Japan for a while, you know?
The readings are 徳 and the vocab 川 put together into one word. Once you can read this, you'll know the meaning too, so focus on the reading for this one.