1.You finished the Story
2.You're married
3.You have a child

A few days after your child runs around your house, there is
going to be an event that shows, how it finds a crystal shard.

After that you have to follow the markers and defeat some bosses
on some floating islands.

When you get all shards theres another event and you can now use a portal
from the heavenly realm to the "Forest of Endings"

There are also some frog statues in there, if you are like me and where searching for the remaining ones ;D