In "Demon Slayer," the lightning technique, also known as Thunder Breathing, is a combat style used by certain characters in the series. Thunder Breathing is considered a powerful and advanced form of swordsmanship that involves channeling the user's strength and determination into lightning-fast strikes and movements. The significance of this technique lies in its speed, precision, and destructive power, making it a formidable ability in battles against demons and other adversaries. Thunder Breathing is often associated with characters who possess great skill, resolve, and a strong sense of justice, reflecting their determination to protect others and defeat evil.