As far as the party knows, Nan Kurayami had been a Robot Battler for a little over a year before he came into contact with the team. As more situations started to arise, Nan started to work in conjunction with them. First more of a lone wolf, Nan gradually starts warming up to the team, although still not very trusting of some of the team members. He has some sort of connection with the Collector that the team doesn't know much about, but apparently Nan has been involved in fighting rogue Snufundays in the past. Nan seems not very trusting of people from other dimensions, and doesn't seem to like the topic of dimension travel in general. But more recently, if anything just giving up to peer pressure, he's gotten more light about it and he seems to be trying to get along with the team more. If anything, because they're probably the only friends Nan has.
...If Doram ever tried to do any digging on Nan's past, not much was found. No records seem to be found about Nan, besides ID and stuff related to Robot Battling.
He lives alone in a house in the same city everyone else lives in. During a battle alongside the Robot Battlers, some sort of Unicorn came to him. It is unknown why the Unicorn chose to side with him, but he is now capable of summoning this creature whenever needed in battle. The Unicorn is fast, capable of flight and can strike with its horn.
The abilities of Nan himself... he is highly capable in close quarters combat, and can use his Dark ability (which seems to be related to his spirit) to empower his strikes and reduce the damage he takes. He is also capable of using guns (assault rifle and pistol) and other weaponry to a certain extent, but he mainly fights barehanded and has not used guns in a while.