The siege of Arai was among the first steps taken by Hōjō Sōun

Hojo Soun

was the first head of the Late Hōjō clan, one of the major powers in Japan's Sengoku period. Born Ise Moritoki, he was originally known as Ise Shinkurō, a samurai of Taira lineage from a reputable family of Shogunate officials...

 towards becoming one of the most powerful warlords of Japan's Sengoku period

Sengoku period

The or Warring States period in Japanese history was a time of social upheaval, political intrigue, and nearly constant military conflict that lasted roughly from the middle of the 15th century to the beginning of the 17th century. The name "Sengoku" was adopted by Japanese historians in reference...

. After attacking Kamakura

Kamakura, Kanagawa

is a city located in Kanagawa Prefecture, Japan, about south-south-west of Tokyo. It used to be also called .Although Kamakura proper is today rather small, it is often described in history books as a former de facto capital of Japan as the seat of the Shogunate and of the Regency during the...

 in 1512, Hōjō turned to Arai castle, on a peninsula to the south, which was controlled by Miura Yoshiatsu.

Miura Yoshiatsu's son Yoshimoto, believing defeat to be inevitable, took his own life by chopping off his own head.