NCHAR VARYING(n) is a variable-length character string type. For details, see description and note of NCHAR(n). The difference is that the right part (trailing space) of the character string is not filled with whitespace characters, even when the number of strings is smaller than n.
NCHAR VARYING(n), NATIONAL CHAR VARYING(n), and NATIONAL CHARACTER VARYING(n) are used interchangeably.
If you specify '큐브리드' as NCHAR VARYING(5) in the EUC-KR encoding, it is processed normally.
If you specify '큐브리드' as NCHAR VARYING(5) and then use CHAR_LENGTH() function in the EUC-KR encoding, 4 is stored.
If you specify '큐브리드' as HCHAR VARYING(5) in the utf-8 encoding, an error occurs (UTF-8 character set is not supported).