sql server – Japanese_Unicode_CI_AS japenese value in varchar

I am loading a table with Japanese name frin CSV those are changing into a question mark. Table has varchar column – I know that varchar column is not Unicode that’s the reason it is happening. However, how come existing value written Japanese are store in varchar while ideally is should be in nvarchar

Is there a way to convert nvarchcar to varchar. Database is out of our control and we can change schema.