Learning Japanese is so hard. I tried to learn it for a year once in school but I didn't do very well at it ಥ_ಥ I'm positive if you keep studying and trying you'll pass that test!
And yes fast food and retail are very mind numbing not to mention a lot of customers are horrible. I work retail right now in college and I'm lucky I get to work in the back because the few customer interactions I've had haven't been great.
I'll be hoping the best for you! (✿◠‿◠)