We were unable to get the "Faith in Friends" Steam achievement for viewing all stories. We have 329 stories unlocked.
According to another guide by kazeneko27, there should be 329 stories for the Steam achievement. It's worth mentioning that this person also had issues getting it to trigger, but was eventually awarded the achievement.
If you're having trouble unlocking all the stories, make sure to try the following:
- Speak to everyone in town with each girl. You can switch your active girl from the System menu. You'll have to switch between the girls many times.
- Do all fetch quests at the Academy.
- Use the Talk option at the Academy Shop.