I've brainstormed some ideas, although you probably already have most of them, so I've started:
Cooking/potions/alchemy system.
A system that allows to create drinks and objects by fusing them.
Event home new home due to a storm you lose your current shelter, however thanks to your friends you create a whole new home, this would have a garden and other functions besides being able to expand to receive tenants.
Event: a cup of coffee
This event is unlocked when you reach the second stage of the dating state, when orin and company give you full access to their home. You can also make a quick trip if you get caught in the early hours of the morning.
Expanded areas:
An expansion available temporarily or upon meeting certain requirements, moon field(only available on full moon upon meeting certain advancements with said spirit(needed to reach level 2 of the relationship), Deep cavern to explore the cave with a certain object you will discover a sector not previously explored by you, eastern border gate, spiritual village underwater cave and underwater ruins, echo waterfall.
New exploration objects:
Lamp allows you to explore certain areas, eagle claw allows you to climb in certain places, clock(allows you to adjust the orario),needed to access certain areas.
Sex toys system:
Unique and functional when you reach level 2 of the relationship.
Clothing systems for the player:
Allows you to wear clothes or not you decide.
Event a change of appearance.
Unlock hairstyles.
Idea potential enemies and that would be what I have for the moment.