The Ritual of Nukabukuro is a written record from Ghost of Tsushima's Records set, left by locals during the Mongol invasion. You find it at Umugi Cove in Toyotama, and it counts toward the Avid Reader trophy.
Go to Umugi Cove in Toyotama and look for the paper or scroll to read. Umugi Cove is a settlement, so you can usually walk in and look around once the area is safe.
Also at Umugi Cove: the Umugi Bamboo Strike, the record Necessary for Survival, the record Outcasts, the Pillar of Honor with the Warrior's Faith sword kit and a Hidden Altar on the boardwalk.
Necessary for Survival
Necessary for Survival is a written record from Ghost of Tsushima's Records set, left by locals during the Mongol invasion. You find it at Umugi Cove in Toyotama, and it counts toward the Avid Reader trophy.
Outcasts
Outcasts is a written record from Ghost of Tsushima's Records set, left by locals during the Mongol invasion. You find it at Umugi Cove in Toyotama, and it counts toward the Avid Reader trophy.
Umugi Bamboo Strike
The Umugi Bamboo Strike is a sword-timing challenge at Umugi Cove in Toyotama. Cut through all the bamboo with the right buttons and it counts toward raising your maximum Resolve.
Umugi Cove Pillar of Honor
The Umugi Cove Pillar of Honor is a memorial shrine at Umugi Cove in Umugi, Toyotama. Visit it to collect the Warrior's Faith sword kit, a cosmetic look for Jin's katana and tanto.