Never had a problem finding a friendly bar in central Hiroshima. I tend to seek out places that serve the local nihonshu - it's unfashionably and unapologetically not so dry.

If you're there on Christmas Eve (it seems you are), then I recommend that you go to the cathedral in the evening. When I went a few years ago the church was full to overflowing and I enjoyed the service and a cup of coffee with the crowd outside. It was a good atmosphere and at the time I felt it was a "real" Christmas in a way that I hadn't experienced in any part of Japan before.