Hammer is the navigator of the Elsa Von Brabant and has a vast knowledge of the net, and at times his opinion on how to fly the ship clashes with that of Tony's (the Elsa's pilot). In spite of the fact that its his job, Hammer doesn't seem to like scavenging the wreckage of starship disasters, like the wreck of the Woglinde.
According to Enneagram personality assessment, Hammer is classified in the behavior-aspect as a type-7 characteristic (talent-rich, impulsive, extreme, high-spirited).
Hammer was the owner of talent and skill to the point of having won fame for being a hacker prodigy when he was approximately in his teens, and due to being a young man of impulsive curiosity, he ended up penetrating the database of some crime organization, and his life had become a target. He fled from place to place away from the crime organization to companions, but before he knew it, he had been cornered. The very character who rescued Hammer from that was Matthews. Ever since then, it came to be that Hammer works as the navigator of the Elsa.
A renowned hacker as a teenager, he got cocky and made a move on a certain criminal organization's database, and became targeted for retribution as a result. Saved by Matthews, their relationship has continued since then. He is the childhood friend of Tony, the helmsman.
At the end, Hammer is one of those who embarks on a mission to find Lost Jerusalem, the lost homeland of humanity.
- Hammer's role is almost useless - he's a navigator in a futuristic spaceship era. Tony asks him, "Why don't you just direct-link it?!" and Hammer replies, "Isn't it obvious?! It's way cooler to navigate by hand!"
- He resembles a non-anthropomorphic animal version of a similar character also named Hammer in Xenogears.