The inventory can be accessed through this button:
After clicking on an item, the right side pane contains the item's name, the quantity owned, and a description of the item. The blue button at the bottom, when applicable, will allow you to use the item.
Inventory Top Row
Marriage Ring and Papers: For the provisional Marriage system.
Medals: Earned by clearing Extra Operation maps and Event maps. These can be exchanged for Remodel Blueprints or a pittance of materials.
Improvement Materials: Used in Akashi's Improvement Arsenal once you've acquired an Akashi
Morale Food 'Irako': Morale boosting desserts to boost ships to 'sparkling' status. Available through some Quests. See more at Morale/Fatigue
Present Box: Special drops available only during a certain time of the year.
Special Chocolate: Another item only available during a limited time of the year.
First Class Medal
New Aircraft Blueprint
Inventory Top Middle Row
Furniture Box Small: Contains 200 Furniture Coins
Furniture Box Medium: Contains 400 Furniture Coins
Furniture Box Large: Contains 700 Furniture Coins
Morale Food 'Mamiya': Morale boosting desserts to remove fatigue. Available through some Quests. See more at Morale/Fatigue
Remodel Blueprints: Blueprints used for some ship's Second remodel. Costs 4 Medals.
Furniture Fairy: Special carpentry fairies for building certain Furniture items.
Headquarters Personnel
Reinforcement Expansion
Inventory Bottom Middle Row
Instant Repair: "Buckets" to restore ship HP to full instantly in the Docks
Instant Build: "Blowtorches" to instantly complete a ship construction in the dry dock.
Development Material: Item consumed when Constructing new ships or Developing new equipment.
Dock Key: Used to unlock additional repair docks and construction dry docks
Repair Team: Equipment used to prevent a ship sinking. See the Repair Team for details.
Repair Goddess: Equipment used to prevent a ship sinking. See the Repair Goddess for details.
Hishimochi
Okazari Material / Saury : Special drops available only during certain seasons. They are used for quests, can be traded in for rewards, and disappear when their season ends.
Inventory Bottom Row
Skilled Pilot
Prototype Catapult
Ne-Type Jet Engine
Canned Saury
Battle Rations
Maritime Resupply
"Construction Team" (for LBAS)
(empty?)