The Archery Master's Attire is Sensei Ishikawa's outfit, once a New Game+ armor set and now a dye for Tadayori's Armor. Its archery perks match a fully upgraded Tadayori's Armor, and you buy it from Baku the Voiceless with Ghost flowers.
In New Game+, visit Baku the Voiceless at Lake Izuhara and buy the dye, then apply it to Tadayori's Armor.
The perks equal Tadayori's Armor at level V, so the dye route gives you the same bow bonuses once you upgrade that set.
Aaruul
Aaruul is one of the 50 Mongol Artifacts, pieces of the invaders' culture and warfare you can study. It sits at a camp south of Izuhara Clearing in Izuhara, and finding 20 artifacts counts toward the Know Your Enemy trophy.
Adachi Dragon Mask
Adachi Dragon Mask is a New Game+ mask sold by Baku the Voiceless for 5 Ghost flowers. It does not exist in a first playthrough.
Adak Tree
Adak Tree is one of the 50 Mongol Artifacts, pieces of the invaders' culture and warfare you can study. It sits at Yoichi's Crossroads in Izuhara, and finding 20 artifacts counts toward the Know Your Enemy trophy.
Adventurer's Fortune
Adventurer's Fortune is a dye for Traveler's Attire. It costs 10 flowers at the Izuhara merchants. Like every dye it only changes colours.