MF leaf shutter lenses usually have a five-bladed aperture. If the lens then has neutral bokeh (as Ken Rockwell defines it on his web site), then out-of-focus highlights show up as well defined pentagons. Some like it or don't mind. Like you, I don't like it.

Konica could afford to make a more rounded aperture on your 50 because as a rangefinder lens, it doesn't have to stop down just before exposure.