Personally inscribed dedication in gifted book?

So I am gifting a book to a Japanese person. It's a nicely designed collection of German poems gifted as a farewell gift.
I was told that books, especially poem collections, are a good gift for a relationship revolving around education since I helped her with German and she helped me with Japanese.
I was also told, that you would inscribe a personal dedication especially if it was a farewell gift.
Is that true? And if so where and in which language would I write it? (The book is in German, but she was teaching me Japanese)

Thanks in advance!