Kazuhisa Adamura (阿多村和久, Kazuhisa Adamura) is the illegitimate youngest son of Jingorou Adamura. He was raised by his prostitute mother until she died, at which point Jingorou took him in with the intention of potentially making him his successor. He is also the lover of Nana Kiyojima.
Kazuhisa is described by Izaya as a 'realistic ideologist'. He's something of a good person, desiring nothing to do with his families shady business.
Born to an unnamed prostitute and his father, Jingorou, Kazuhisa was raised primarily by his mother for most of his life. When he was a teenager, his mother was killed, prompting Jingorou to take him in. His half-brothers, Ryuuichi and Ryuuji, dislike him and don't quite consider him family since he only carries half of their blood. However, Jingorou reassures Kazuhisa that he considers him his son and that his brothers would do the same unless they were questioning his choices with the women 'he selected and paid for.'
The Adamura family deals in various parts of the underworld, they are also tense rivals with the Kiyojima family. Prior to being taken into the Adamura family, Kazuhisa had begun to date Nana Kiyojima. After entering the Adamura family, he's forced to hide his relationship, though the Candiru expose it to his father. Weary of the illegal dealings his family works with, his father and him have a conversation pertaining to his future. Jingorou tells him that he's free to leave and get an education, however, he won't be sheltered in their estate any further, or he could remain and become the successor to the family business.