Eternal Graves

Structural lore — Ringo’s burial custom. Mysteries live in Vault/Threads/; this is what the world IS.

What we know

Ch. 953: A burial custom of Ringo, the snowbound northern region of Wano (pp. 6, 8). The land is so cold that coffined bodies “remain preserved for centuries.”
Ch. 953: Ringo folk are gifted a katana at birth, live with it, and are buried with it stuck upright into the ground as a grave-marker — so the graveyard is a field of standing swords.
Ch. 953: Some of these blades are “of legendary make,” which makes grave-robbery a constant problem.

The custom underwrites two plot beats in Ch 953:

Gyukimaru guarding Shimotsuki Ushimaru’s grave alone for years, fighting off grave-robbers.
Kawamatsu harvesting the grave-swords into a hidden underground cache to arm the Kozuki rebellion against Kaido — overcoming Orochi’s 20-year confiscation of Wano’s weapons.

How many warriors can Kawamatsu’s grave-sword cache actually arm, and where is it hidden? (Tracked in Kawamatsus Hidden Sword Cache Arms The Kozuki Alliance.)