Kasumi's grandfather

Kasumi's grandfather was a mechanic, and the creator of the long-range boats that the player takes to Far Harbor.

Background
Kasumi's grandfather was a technologically adept scavenger that made a living fishing and combing the ruins for useful tech. He trained Kasumi Nakano in the construction and inner workings of circuitry. Despite his age, he continued to work with his granddaughter and scavenging for parts. He helped Kasumi to restore appliances around the house until his unexpected death, and encouraged her to keep logs of her projects. It is implied through dialogue with Kenji that he was aware of the radioactive fog surrounding Far Harbor during a trip to the island.

Appearances
Kasumi's grandfather is only mentioned in the Fallout 4 add-on Far Harbor.