Cecec will sell rare outfits at her shop after you've done all the sidequests there, including the Hylian Shield, but at a massive cost.

Source: https://www.digitaltrends.com/gaming/zelda-tears-of-the-kingdom-hylian-shield/

Substories are what sidequests are called in Like a Dragon: Ishin!

Source: https://www.digitaltrends.com/gaming/like-a-dragon-ishin-substory-locations/

While the main plot obviously shouldn't be disregarded, providing more information on the Evokers in following the original game may not make time for extra missions or sidequests, but it could open the door to more exposition.

Source: https://gamerant.com/persona-3-reload-evoker-lore-mystery-answers/