Asking manager for one day a week off?

I just started a job at a supermarket that I worked at two years ago, to supplement the 4 day a week unpaid internship I am doing. When I was hired for the supermaket job, I was originally hired for Fridays, Satrdays, and Sundays. I really feel bad doing this, but I may have to work there only Fridays and Saturdays and have Sunday off, for two reasons. One, the job is not in my town, so i have to takt the bus and the bus doesnt run on Sundays. Two, as of right now im working with both the internship and job, 7 days a week, from early morning to late at night. Do you think it would be reasonable to ask my manager if it would be possible to work just the Fridays and Saturdays?

Sure-as a manager, I would rather have someone tell me and give it to them off and have it covered rather then them not being able to make it because of no bus/ride. Talk to him and let him know-if he doesn't understand find a job that is willing to give you what you need-I think they will work with you though.

I wouldn't be afraid of asking. You still will be working two days, and the manager may have someone who wants more hours and now the manager can possibly make two people happy.
I can't see a downside. If the manager says no then you have a decision to make, but you won't know that until you ask.

Its not unreasonable to ask, but if the manager absolutely needed you all 3 days, be prepared for him to tell you that your new schedule doesn't meet the needs of his business and that you'll need to part ways. He may also say, fine, no problem, just depends on what the store's needs are. Good luck.