volcanic crater rim; the rim of a volcano
Specifically refers to the sharp, sword-like ridge around a volcanic crater, most famously associated with Mt. Fuji. Often used in the phrase 剣が峰に立つ (to stand on the rim) metaphorically.
The crater rim of Mt. Fuji is the final challenge for climbers.
sumo ring; wrestling ring
In sumo, the raised ring where matches take place. The term evokes the idea of a critical boundary, similar to the crater rim.
When the wrestler stepped onto the ring, applause erupted from the audience.
critical situation; sink-or-swim moment; do-or-die position
Metaphorical use derived from the crater rim sense. Describes a high-stakes situation with no room for error, where one wrong move leads to disaster. Common in business, sports, and personal crises.
The company is in a dire cash-flow situation, truly standing on the brink.
In the final set, at the critical moment, an ace was scored.
Standard kanji spelling using が; the most common written form.
Variant using the small ヶ (katakana ke) as a shorthand for が; often seen in place names and signs.
Rare variant with full-size ケ; may appear in older texts or specific proper nouns.
Literally 'sword peak' (剣 = sword, 峰 = peak). Originally referred to the sharp, sword-like ridge of a volcanic crater, especially on Mt. Fuji. The metaphorical sense of a critical situation comes from the image of standing on a narrow, dangerous ridge.