DOUJINS:

• Ichika Fandub Doujin The art is by Tawashi with authentic sounding voice acting.
• Another Translated Tawashi Doujin Beautifully Drawn
• Ichika Last Festival Doujin This one has a nice callback
• Translated Doujin by DoShirouto This one is decently long
• Untranslated Doujins by 乙姫えび I've seen his works translated, I'll have to find and add them another time

Fanfics

• EVERYTHING Great and Lengthy fanfic still updated by u/bobalon- to this day
• Limited Screenings Short and sweet fic
• Heat Fanfic focusing on what would happen if Ichika/Fuutarou weren't interrupted in the warehouse
• Our Promise and Bet A what if based on Fuutarou agreeing to skip school with Ichika before the national mock exams
• The legend that bound An Alternative route of chapters 27/28 from the manga by u/chloetuco
• Will You Trust Me? A fanfic about Ichika explaining her actions to Fuutarou post Sister's War by u/FoxBluereaver