The Legend of Tadayori is a Mythic Tale in Azamo, Izuhara, about a famous archer and the kami-blessed armour he wore. Finishing it gives you Tadayori's Armor, the set to wear if you fight mostly with a bow.
Part 5 of 9 in Mythic Tales
Tadayori Nagao was the best archer on Tsushima, and the war kami Hachiman gave him his own armour. When pirates attacked Azamo Bay, Tadayori held the town alone and no blow got through. After he died the armour vanished, and his family is said to guard it still.
Ride to northern Azamo and look for violet flowers. They lead to the Violet Crown, east of Kii's Pond, where you find fresh incense and a map. The map takes you to Tadayori's Rest, a cemetery where Kaede mistakes you for a thief and duels you. After the fight she gives you a line from an old scroll pointing to a peak above Azamo Bay.
At Azamo Bay, Mongols are holding Yamato after forcing him to read a scroll about the armour. Free him, grab the armour, then defend the musician from the rest of the Mongols. Talk to Yamato to finish.
Pair this armour with the Longbow from The Curse of Uchitsune. Faster draws and extra Concentration make up for the Longbow's slow pull.
The Curse of Uchitsune
The Curse of Uchitsune is a Hiyoshi Mythic Tale in Izuhara, where you search for a legendary archer's cursed bow. Finishing it gives you the Longbow, the longest-range weapon in the game, plus Explosive Arrows.
The Heavenly Strike
The Heavenly Strike is the first Mythic Tale, set in Komatsu in Izuhara. You hunt a killer who wants Shigenori's legendary sword technique, and finishing it teaches you the Heavenly Strike, a fast unblockable katana attack.
The Six Blades of Kojiro
The Six Blades of Kojiro is an Umugi Mythic Tale in Toyotama, where you duel five Straw Hat assassins and then Kojiro himself. It has more duels than any other single tale, and it rewards the Kensei Armor, a set that boosts Resolve and Ghost Weapons.
The Spirit of Yarikawa's Vengeance
The Spirit of Yarikawa's Vengeance is a Mythic Tale in the Ruins of Old Yarikawa, Toyotama. You follow offering shrines to a vengeful spirit and learn the Dance of Wrath, a three-hit unblockable katana technique.