To be honest,like the other members have pointed out,Japan has a miniscule muslim population to make claims of harmony or otherwise.In experience of north east India (the culture and mindset is more eastouth-east asian than south asian here),the muslims at first prefer to be left alone and do not interact much with others,as soon as they have significant numbers they try to force their beliefs on others.Disrespecting the native beliefs and way of life,restricting themselves to ghettos and creating social issues etc.So no,Islam especially its more purist strains are incompatible with others people,at least in north east India.