The Charm of Izanami is a major Defense charm, named for the kami of life and death, in Ghost of Tsushima. When Iron Will saves you from death, you come back with half your maximum health. You get it by honoring the Marsh Rock Shrine in Toyotama.
Climb to the Marsh Rock Shrine, northeast of Akashima Village in Akashima Prefecture, and honor it at the top.
Iron Will normally leaves you close to dead, so this turns a last stand into a real second chance.
Akashima Bamboo Strike
The Akashima Bamboo Strike is a sword-timing challenge near Fort Ito in Toyotama. Cut through all the bamboo with the right buttons and it counts toward raising your maximum Resolve.
Akashima Haiku
The Akashima Haiku is a poem spot where the river meets the sea, just south of Old Kanazawa Marsh in Toyotama. Sit down, pick three lines and you earn the Headband of Uncertainty.
Akashima Lighthouse
Akashima Lighthouse is one of the 10 lighthouses Jin can relight, at Fort Ito, Toyotama. Lighting the fire gives a minor boost to your Legend.
Amber Assassin
Amber Assassin is a dye for Ronin Attire. It costs 10 flowers at the Toyotama merchants. Like every dye it only changes colours.