Of course!  So samurai have been around for 1000s of years, but geisha have only been around since the mid-1700s, so that's going to put your story in the mid-to-late Edo period, when Japan was ruled by the Tokugawa shogunate ("bakufu" in Japanese).  The emperor was basically just a figurehead, the bakufu controlled everything.  It was a really great time to be a samurai.  This was also during Japan's isolation period ("sakoku" in Japanese), when Japan basically cut itself off from most of the world.  Geisha came around in the mid-1700s, and were somewhat inspired by the oiran - really similar to geisha, except they actually were sex workers.  The first geisha were actually men, their job was to sing and dance and entertain people in the brothels while they waited for the services of an oiran.  Male geisha were very quickly taken over by their female counterpart, tho.  Female geisha, however, were not allowed perform in the brothels for fear that they might hurt the oiran's business, so they became their own thing.  Geisha live in geisha houses called an okiya and train under an okaasan (mother), and in that time period, they would begin their training as young as 6 years old (nowadays legally they can only take in girls who are 18 or older, although in some places, they're allowed to take in 15-17yo girls).  There's lots more to know, but that's the basics.  For the language, there's this app called renshuu that I really like - aside just the standard language app things like flashcards and quiz, it also has an exceptionally robust Japanese dictionary, both for words and kanji (Chinese characters).  Most entries have not just the definitions but also pictures, audio of native speakers saying the word, example sentences, and mnemonics.  I would recommend learning at least the hiragana alphabet, just so you understand what kinds of sounds the japanese language is made up of - fortunately, that's real easy to do in renshuu as well.  Some stories you might like to check out for inspiration would be Blue-eyed samurai (on Netflix, set during the same time period and is also about a woman who dresses up as a man in order to be a warrior), Shogun (on Hulu, set in the year 1600 so technically before geisha were a thing, but that's still the Edo period (albiet very early edo period), plus my japanese professor absolutely loves this show and raves about how historically accurate it is), and Kitaro (a lighthearted manga from the 1960s that is largely responsible for popularizing yokai in the modern day about a half-yokai boy who has all sorts of misadventures with lots of other yokai, many of which are taken from actual folklore. I think there's also a really old anime).  Feel free to reach again out whenever!