Follow the path outside, where a cutscene will play of a tengu monk warning you away from the Uchitsune's longbow.
Once you're done, go back out via a crack under the wall behind you. Head inside to the little shrine and examine it to find a picture of an island. Head to the marked area on your map and head to the very centre of the searchable circle to find a buried tomb at the base of a huge rock, blue hydrangeas leading up to a crack that'll let you in.
The first step is to find the hidden tomb on the coastline, though Jin won't know that's what he's looking for. | Joel Franey/USG, Sucker Punch Productions/Sony Where to Search the Coast The tomb is in the very middle of the first area. Yamato says he knows that Uchitsune liked to walk Hiyoshi's coastline and observe the blue hydrangeas, giving you a starting point to search for it. Uchitsune began to see the demon everywhere, and killed numerous people in his confusion, eventually exiled to Tsushima and dying quietly, his longbow lost somewhere. Once you find Yamato, he'll give the you the backstory behind this quest: Uchitsune was a renowned demon hunter who was hired to kill a Kami with his longbow, only to be cursed in the demon's last moments. To begin the Curse of Uchitsune in Ghost of Tsushima you'll first need to find an NPC who can tell you where to start the quest, a process we've laid out at our guide to starting all the Mythic Tales here. The Curse of Uchitsune Mythic Tale Walkthrough in Ghost of Tsushima Is the Longbow Better Than the Half-Bow?.The Curse of Uchitsune Mythic Tale Walkthrough in Ghost of Tsushima.We'll show you the steps you need to take in our "The Curse of Uchitsune" Mythic Tale walkthrough. The Curse of Uchitsune is one of Ghost of Tsushima's most notable Mythic Tales, a quest across Hiyoshi to find a rare longbow said to torment whoever holds it.