Origin

The kanji 扉 combines a door radical (戸, which depicts a swinging door) positioned on the left with a sound hint component (非) on the right. The sound component 非 provides a rough pronunciation guide rather than adding to the meaning. Together, these elements create a character specifically for doors and related openings like the cover or title page of a book, which is conceptually similar to an entryway. The visual emphasis on the door component keeps the meaning grounded in the idea of a threshold or entrance.