赤

1. Origins, structure, and basic meaning

• Structure: Written 赤 and read あか, it denotes the color red and can also identify red as the medium used to mark something.
• Basic usage: It appears when a signal turns red and when a circle is drawn in red on white paper.

2. Common pitfalls and similar expressions

• Color name versus marking medium
  • Context can name the color itself or imply using red ink, paint, or another red medium.