String::Multibyte::ShiftJIS is used for manipulation of strings
in Shift-JIS family encodings.
Byte range of single-byte characters:
0x00..0x7F and 0xA1..0xDF.
Leading byte range of double-byte characters:
0x81..0x9F and 0xE0..0xFC.
Trailing byte range of double-byte characters:
0x40..0x7E and 0x80..0xFC.
Character order (invalid code points are excluded):
0x00..0x7F, 0xA1..0xDF, 0x8140..0x9FFC,
0xF040..0xFCFC are included.
0x80, 0xA0, and 0xFD..0xFF are not supported.
For Shift_JISX0213, row 8 of the plane 2, 0xF09F..0xF0FC,
is simply arranged in the binary order
(This module is not aware of the JIS X 0213 order).
Then, row 1 (0xF040) < row 8 (0xF09F) < row 3 (0xF140) ...