Kei Nanjo, referred to by his fellow students by his last name Nanjo, known in Revelations: Persona as Nate, is heir to the Nanjo family fortune and is a well-meaning snob. He is followed everywhere by his devoted family butler, Yamaoka. Nanjo apparently does not spend much time with his parents, so Yamaoka's death at the hands of zombies deeply affects him. Because he and Takahisa Kandori mingle in the same social gatherings, Nanjo knows the most about him than anyone else in the party. Nanjo shows a ruthless degree of pragmatism, and has nothing but dislike for the outspoken Masao. Masao hits Nanjo in the face after the latter advises that Maki should die in order to restore order to the city. Nanjo also encourages the main character to allow a SEBEC scientist to die, as a consequence of an attempt to stop Takahisa.
Nanjo wields two handed swords as his melee weapon. His long-range weapon is a hunting rifle with sight. His initial Persona is Aizen Myouou. Nanjo wears a blue scarf with an embroidered "#1" in addition to his uniform.
In Persona 3, Mitsuru Kirijo mentions that the Kirijo company is no longer under the Nanjo group, referencing Nanjo's company.
Nanjo is also a guest on the television show 'Who's Who', a show about previous Persona characters and what they are doing now. He is described as "a man in his 20's who is proud of his intelligence". He can be identified by all the #1 designs on his clothing.