If this is effected, it is not only high but exorbitant which can be said to be suicidal. 55% even the highest I know of is 35% and that is for corporate organisations in which even the US government is reviewing its own downwards to ensure there is much more disposable income in the private sector and with that they can expand, create more jobs, and it turns to more money for government in form of taxes all over again.
What I am seeing here is a strategy by the Japanese government in the sense that, they want to allow crypto but dont want it to change their social order by giving more money to the hands of the individuals engaging in crypto because an 18 year old boy making the right decision in crypto can be a millionaire before 20, spread across the whole country means some level of independence which they might not be able to control if it circulate throughout the country and that is government losing their influence over the citizenry.