The Left White Corner Bracket symbol (『). Copy and paste it, or use its Unicode, HTML, and CSS codes.
More from Punctuation.
The quickest way is to copy 『 from this page and paste it anywhere. You can also insert it with its Unicode, HTML, or alt code listed above.
『 is U+300E (decimal 12302).
Use 『 in HTML to render 『 on a web page.
On Windows you can type it with Alt+12302 (hold Alt and enter the number on the numeric keypad).
Yes — copying is completely free and unlimited, and works right in your browser with no sign-up.