Yuki has been the first to gain a personal item of an NPC, one that grants a special ability. These are riddled about the Ship, though most will not become personal unless a great Feeling is expressed in gaining the item.
Kasiei's Sunglasses - These Sunglasses were taken by Yuki from the Corpse of Kasiei, who died protecting her. These sunglasses were bought for Kasiei by Yuki, and was what cemented the friendship and Parental Relationship between the two. As long as this is in her inventory, she can, once per fight, invoke a special skill known as 'Father Kasiei', where Kasiei's Spirit will come and fight with Yuki to protect her. It also prevents her from having the 'Fear' Status effect.