The Negoro Group was a band of warrior monks residing in an area centered around the Negoro Temple in the northern part of Kii Province during the Sengoku period. Similar to the Saika Group, the members of the Negoro Group armed themselves with arquebuses and operated as a band of mercenaries. In terms of capability as well as capacity, the Negoro and Saika groups were known as the most potent armed bands in the Sengoku period.
The primary members of the Negoro Group included the Tsuda clan led by Tsuda Kazunaga, based at one of the priests’ quarters at the Negoro Temple known as suginobō, along with the powerful Shimo clan from Kumatoridani in Senshū (Izumi Province). A monk named Sugitani Zenjūbō was well-known for sniping Oda Nobunaga, but the Negoro Group was on friendly terms with Nobunaga and joined in the Conquest of Kishū as well as the Kyōto Mounted Horse Parade.
After followers of the Ishiyama-Hongan Temple fought against Oda Nobunaga at the Battle of Ishiyama, the Hongan Temple joined forces with the Negoro and Saika groups of Kii. As a first line of defense, the Negoro Group proceeded to build between five and seven outlying castles in Izumi Province. This included Sengokubori Castle. During the Invasion of Kishū by Nobunaga in 1577, some members of the Negoro and Saika groups joined the Oda army. Those defending the castles constructed by the Negoro and Saika groups abandoned their posts without fighting and withdrew by sea.
From the third to eleventh months of 1584, the Battle Komaki-Nagakute was waged between Hashiba Hideyoshi and the combined forces of the Tokugawa and Oda clans. The conflict raged in many provinces, including Owari, Mino, Ise, Izumi, Settsu, and Kii, triggering additional battles across Japan. Hideyoshi achieved a strategic victory, marked by individual settlements with Oda Nobukatsu and Tokugawa Ieyasu, leaving isolated the Negoro and Saika groups of Kii, as well as Chōsokabe Motochika of Tosa Province in Shikoku. Continuing their resistance, the Negoro Group joined the Saika Group by attacking Ōsaka, striking fear in Hideyoshi. This led, in 1585, to separate invasions by the Toyotomi army of Kii Province to subdue the Nagoro and Saika groups and of Shikoku to subdue the Chōsokabe clan.
Early in 1585, Hideyoshi launched the Conquest of Kishū. In the third month, the army of Hashiba Hidetsugu emerged victorious at the Siege of Sengokubori Castle in Izumi. After the start of the offensive by the Hashiba forces from the environs of Kyōto, the other outlying castles of the Negoro and Saika groups in Izumi were toppled over a period of days. This was completely unexpected by the Negoro and Saika groups in Kii. To preserve their power, whenever possible, sengoku daimyō sought to avoid conflicts that would lead to severe economic and military losses. Therefore, in situations where the advance forces incurred significant damage, the lords would generally pull-back to avoid further loss. Consequently, from the perspective of the Negoro and Saika groups, no matter how large the Hashiba army, there was a belief that if they could overwhelm the advance forces, then they would not need to confront the entire opposing army. At this point, however, Hideyoshi already wielded enough power and soldiers to overwhelm other daimyō, so he was not unduly focused on the preservation of resources. As a result, the thinking of the Negoro and Saika groups missed the mark.
On 3/23 of Tenshō 13 (1585), to confirm the subjugation of Izumi, Hideyoshi departed from Kishiwada Castle and headed toward the Negoro Temple. The primary forces of the Negoro Group had been deployed to the front lines in Izumi, so there were few remaining to defend the temple. After the remaining monks fled, the castle was taken with almost no resistance. That evening, the temple was set on fire, turning to ash the main hall and towers, and leaving only a portion of the premises including the southern gate. The temple burned for three days, turning the sky a reflective color red that could be observed from the Hongan Temple in Kaizuka. There are assorted theories concerning the cause of the fire, including that it was set by the Negoro members, by Hideyoshi, or by soldiers acting without orders. That same day, or on 3/24, the Kokawa Temple also burned.
In Kii Province, Negoro Daizen (also known as Shimo Morishige) led the resistance of the Negoro Group. Meanwhile, Tōdō Takatora served for the Hashiba in the offensive, forcing the surrender of Yukawa Naoharu in the tenth month of 1585, and, in 1586 slaying Yamamoto Yasutada during a settlement negotiation. Upon orders of Hidenaga, Takatora cornered Suzuki Shigeoki, compelling him to take his own life. After the conquest, fifty members of the Negoro Group who had earlier scattered during the war were assigned to Naruse Masanari, a young retainer of Tokugawa Ieyasu. Known as the Negoro Unit, this group grew to 100 soldiers, making contributions on behalf of Ieyasu at the Conquest of Odawara in 1590. In the ninth month of 1600, the Negoro Unit participated under Masanari at the Battle of Sekigahara, and were later stationed at the newly developed Naitō post town in Edo during the early Edo period.
Around 1600, the Tanaka family, who served as the heads of the Iwamuro priests’ quarters at the Negoro Temple, became retainers of the Mōri clan of Aki Province, adopting the surname of Negoro, and later serving on behalf of the Chōshū domain in the Edo period. Descendants included Negoro Chikasuke who served as a chief retainer of the domain toward the end of the Edo bakufu and his son, Negoro Chikasuke.