There are some types of items in Imperial SaGa, some which mixes SaGa with mechanics that remember some other games.
Growth Orb: Raises probability to learn new waza and stat up.
Imperial Flag: Allows Sudden Army Attack!
Protection Stone: Prevents characters from losing LP.
These items are used outside missions:
Return Orb: Resets character's stats, allowing him/her to grow strong again.
Bed: Adds one Bed to the INN.Up to 5 can be bought.
Time Jewel: Finishes some tasks instantly.
Stronghold: Maximum Character capacity up.
Yellow Healing Potion: Heals completely an ally or awakes character instantly. Can get up to 10. You can get these in 5+ hours in absence.
Red Healing Potion: Same above, except you can buy with Crowns.
Crowns: Main currency in game, can get by buying with Yen or by daily or special Rewards.
Magic Book: Used to learn and intensify magic in the Magic Laboratory.
Scroll: Used to hone and lower SP cost from waza.