SSMS and Unicode fonts in grid results
If you want to insert Unicode text in your update statement you need to supply a Unicode string of the form N'...', as in

update foo set test = N'褠ఓ�ᵂ뱗텬㰗' where id = 1


Otherwise the characters really are converted to question marks if SQL Server is unable to map them to corresponding non-Unicode characters, even in an nvarchar column.