Doors at beginning

[Arukādo]

I can't find any information about this.
There are giant doors at the beginning of the game, when you go right after the first Lightreaper battle. You can see them in Umbral and you can try to open them (there is a prompt) but I don't know how to go behind. Any idea?

[Xero]

Progress the game, you come back to them later as part of an NPC quest.

[PostalGibbon]

You need certain flesh from optional boss in the memorial area to open that door at the beginning.

[Arukādo]

Alright I see which flesh you are talking about, will try soon, thanks!

[BabbaT]

That is the quest of Paladin Isaac. Best is to check the wiki for what to do as his quest can be failed very easily. Good luck and I hope you enjoy the journey.