序曲

1. Origins, structure, and basic meaning

• Structure: 序曲(じょきょく) means an overture and can figuratively describe an event heralding something larger.
• Basic usage: It refers to music opening a concert or a small event that leads into major change.

2. Common pitfalls and similar expressions

• From music to the start of change
  • In a musical context, 序曲 is an overture; 改革の序曲 figuratively means an event heralding reform.