Is new content/story tied to difficulty?

[FurFanatic]

If I play on the lowest or the regular difficulty am I locked out of content, or do I still experience the full story/unlocks? I am fine with that, I just wanted to know if the progress/unlocks are tied to playthroughs alone or also to the difficutly played at.
Thank you so much <3

[Isiel]

The story isn't finished yet, but everything can be seen on any difficulty, iirc. If any of the difficulties would be locked out of stuff it would be Mist, but I'm not sure.

As for unlocks, definitely refer to the dream list. Most of the time, they'll specify any further constraints to unlocking it.

[Veyerals]

No story will ever be locked out of Mist Rain. And by extension, this includes all final bosses.

However, I can think of 1 example where you must complete a specific story path on Heavy Rain to unlock a specific monster, which can then be encountered on any difficulty. There are also 3 monsters that have a minimum level 8 battle which means they can't appear in Mist Rain. This limitation will never apply to any final bosses.