Asano Nagakatsu served as a bushō during the Sengoku and Azuchi-Momoyama periods.  Nagakatsu served as the head of the Asano clan.

Nagakatsu served in an archer battalion for the Oda clan of Owari Province.  During the Tenshō era (1573 to 1593), he built Yasui Castle.  Later, after Nagakatsu moved to the village of Ōzato in the Nakashima District, the castle was abandoned.  He then moved to Asano Castle and, upon orders of Oda Nobunaga, served under Hashiba Hideyoshi.

Nagakatsu did not have a son.  His wife, Nanamagari-dono, had a younger sister named Asahi-dono who was married to Sugihara Sadatoshi.  Their daughters were named Nene (later known as Kōdai-in) and Yaya (later known as Chōsei-in).  Nagakatsu and Nanamagari-dono adopted and raised these sisters.  In 1561, Nene wed Kinoshita Tōkichirō (later known as Toyotomi Hideyoshi) as his formal wife.  Asahi-dono (Nene’s natural mother) initially opposed the marriage on the grounds of social status but was persuaded by her older brother, Sugihara Ietsugu, to permit the marriage with the support of Nagakatsu and Nanamagari-dono.  Owing to this marriage, the Asano became the closest relatives of Hideyoshi, and, following Hideyoshi’s rise to power, played an important role in the Toyotomi administration.

Meanwhile, Yaya wed Yabei (the son of Yasui Shigekatsu and later known as Asano Nagamasa) who became the adopted son-in-law of Nagakatsu and Nanamagari-dono and the heir to the Asano family.