Meaning

To destroy evil and make manifest the true Way — a Buddhist-derived formulation of righteous combat.

邪悪なものを打ち破り、正しい道理を世に明らかにすること。

The Kyojuro Rengoku line

Verbatim from the source article

「この煉獄の赫き炎刀が」

"...MY BRIGHT RED FLAME BLADE..."

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Why it fits Kyojuro Rengoku

The Demon Slayer Corps' entire mission is haja-kenshō — demons are not just enemies, they are 邪 (the wicked), and the nichirin blade is the instrument that "reveals the right." Rengoku's Ninth Form lands as the explicit declaration of that vow.

Cultural note

Origin in classical / Buddhist / Confucian tradition

Originally a Tendai / Nichiren Buddhist slogan describing the dharma battle against false teachings.

Sources

• デジタル大辞泉 — 破邪顕正 (dictionary)
• 精選版 日本国語大辞典 — 破邪顕正 (dictionary)

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