Introduction

Inventory (アイテム) is a main menu function that displays all the items you have earned.

Menu Functions

Owned Items (保有アイテム) - All items that you own. Items must be in this inventory before they can be used.
Purchased Items (購入済みアイテム) - Items that have just been purchased from the cash stop appear here. They need to be moved over to Owned Items before they can be used.
Expanded Inventory (拡張アイテム) - Extra inventory space implemented to fit newly introduced items.
Use Item (使用する) - Available from some items, allows you to use the item.

Expanded Inventory

Standard Inventory
Row	Item Name
1	Marriage Paper	Medal	Improvement Material	Irako	Present Box	Valentine's Chocolate	First Class Medal	New Technology Aircraft Blueprint
2	Furniture Box (Small)	Furniture Box (Medium)	Furniture Box (Large)	Mamiya	Blueprint	Furniture Fairy	Headquarters Personnel	Reinforcement Expansion
3	Instant Repair Material	Instant Construction Material	Development Material	Dock Opening Key	Repair Team	Repair Goddess	Hishimochi	Saury
4	Skilled Crew Member	Prototype Flight Deck Catapult	Ne Type Engine	Canned Saury	Combat Ration	Underway Replenishment	Construction Corps	Submarine Supply Material

Expanded Inventory
Row	Item Name
1	-	-	Action Report
2	New Model Gun Mount Improvement Material	New Model Aerial Armament Material	New Model Rocket Development Material
3	Combat Ration (Special Onigiri)	Emergency Repair Materials	New Model Armament Material
4	Xmas Select Gift Box	-	Setsubun Beans

By clicking on all 3 flowers next to the fairy on the left, a "mini-game" is unlocked.

This consist of an "Anti-Air Defense" game, where a black sheep (reference to Gotland) is thrown to destroy abyssal planes.
This mini-game is just here to "kill time", and so is not linked to the rest of the game, neither consuming nor rewarding anything.