Kizuki Castle is also known as Woniu Castle, Mufu Castle, located in the southwest of the Kunidong Peninsula, east of Shoujiangwan, south of the Yasaka River, this is the residence of the Otomo retainer Mufu clan, after the battle of Wenlu Otomo Yoshitong was changed, Mufu Zhenzhi and Tongzhi committed suicide one after another, and Mufu Castle was collected as Taiko and hid into the ground. After the Battle of Keichaga, Hosokawa Tadashi obtained the territory of Kitsuki and the surrounding 60,000 koku, but because the Hosokawa family's skills were located in Tango, this enclave has been managed by his retainers Matsui Sado Moriyasuyuki and Ariyoshishiro Saemon Tatsuyuki, and there were 1,800 people in the city, but 1,000 were later recalled by Hosokawa Tadashi, leaving only 800 to maintain law and order in the territory.

The geographical location of Kitsuki Castle is not only reflected in the surrounding environment, but also in terms of transportation, it is connected to Nakatsu and Kokura by Hokuhogo through the Hyuga Street, and is connected to Funai and Usuki by Nanhogo to the south, Anki Castle in Kumagai Naomori to the east, and Sunrise Castle in the west by Taiko Kurizori. It can be said that once Kitsuki is captured, Bungo except for the Kunisaki Peninsula can be included in the bag, so in order to obtain food and pay as quickly as possible and suppress Bungo, Kuroda Rusui ignored the two castles of Takada and Furai controlled by the Otomo clan, and attacked Kitsuki directly through the Hyuga Street, intending to end the battle within three days.

According to Kuroda Rusui's prediction, in view of his strong military strength, Otomo Yoshitomo would never send troops to reinforce Hosokawa or attack Kuroda's army, so that once the army captured Kitsuki Castle, obtained sufficient food and grass supplies, and turned around and attacked the Otomo clan again, Otomo Yoshitomo could only be forced to surrender, and the general was handed over to the Kuroda army, and then attacked Nantoyogo and Kita Hinata, which were basically unguarded, to complete the suppression of eastern Kyushu.

However, he didn't expect that the important minister Sonataka Zhenxu under the command of Otomo Yoshitomo would see through this strategy of raising war with war, and persuaded the Otomo clan to send troops to support Matsui Yasuyuki, not only that, but he also sent someone to Kato Kiyomasa Kato to ask for help, intending to work together to suppress the newly emerging Kuroda family.

In fact, Kiyomasa Kato, who is in Higo, has been acting as Hideho's agent in Kyushu, monitoring the every move of the Shimazu and Kuroda families. At first, when he learned that Kuroda Nagamasa led the main force to support Hideho, Kato Kiyomasa was relieved, thinking that the Kuroda clan had not forgotten Taiko's grace after all. Unexpectedly, Osaka's crusade order that didn't know the truth actually made Kuroda Rushui move his mind. These days, they have scattered their wealth to recruit troops, not only the small daimyo in the surrounding area, but also Kato Kiyomasa in Higo and Shimazu Tadashi in Satsuma are all in their eyes.

As an ally of Tokugawa Ieyasu, the Shimazu clan, like the Kuroda clan, did not put all their eggs in one basket, as evidenced by the fact that Shimazu Yoshihiro led 1,500 men to follow Hideho to conquer Aizu not long ago, and it was not difficult for the Shimazu family, who had a height of 650,000 koku, to recruit 15,000 people, but the scheming Shimazu Yoshihiro warned Shimazu Tadashi before leaving that he must not be a leader in this matter. If it weren't for Kuroda, the water would move first. The Shimazu family must remain neutral.

It was learned that Kuroda Rusui was recruiting sergeants. Shimazu Tadashi also immediately took action, deploying a huge army of 12,000 men on the border with Higo and Kita-Hyuga, while Kato Kiyomasa led 7,000 troops eastward to Uchimaki Castle near Mt. Aso, which was only a few miles away from the border with Higo Bungo.

April 14. On the day he received a letter from Otomo Yoshitomo asking for help, Kato Kiyomasa crossed the border between the two countries and entered Bungo, and Nakagawa Ieoka Castle Castle, who had been notified in advance by Tahara Shoshinobi, greeted Kato's army, provided food and grass, and led 500 men to help; When they marched along the streets of Hyuga to Sunrise Castle, Mori Takamasa and Hayakawa Nagamasa each led 600 men into battle, and when they arrived on the banks of the Yasaka River on the evening of the 15th, Kato Kiyomasa had already gathered 8,700 men, plus the 2,800 men of Otomo Yoshitomo stationed on the north side of the Takayama River on the north side of Kitsuki and 800 men in the castle, in just two days. The Toyotomi army's strength increased sharply to 12,300 men, much higher than the Kuroda clan's 9,000 men, and in the face of this situation, negative voices began to appear in Kuroda's army, and some even fled by night. This makes Hei Tian Rushui very worried, it was originally a rabble pulled up by money, and it was not the opponent of Kato and others in terms of fighting at all, it was better to blask if he had an advantage, but now he didn't even have the advantage in numbers, how could he win this battle?

Thinking of this, Heitian Rushui repaired a letter, and asked his cronies and retainers to bring Shimazu Tadashi who was in Satsuma Deshui Castle, and asked him to immediately send troops to attack Nanfeihou, so as to shake the military heart of Kato's army and achieve the goal of encircling Wei and saving Zhao.

Although the envoy traveled at night, but due to the long distance and the need to avoid Kato Kiyomasa's eyeline, it was two days later when he arrived in Satsuma, in these two days, the black sky was like water launched a night attack and an ambush, the night attack was mainly aimed at the north side of the Otomo Yoshitsu army, at first achieved some gains, beheaded more than 200, but when retreating, he encountered Kato Kiyomasa's ambush in the mountains and suffered heavy casualties, and then the pursuit of Yoshihiro Tongyuki was also a burst of slashing, and the night attack team of 2,000 people finally only 300 people fled back to the Rushui main formation, Most of them were not beheaded but fled in chaos, and some ronins even defected on the spot to join the Toyotomi army and attack the Kuroda army together.

Although the number was much higher than that of the Kuroda army, the Toyotomi army was reluctant to take the initiative to attack, but waited for the Kuroda army to run out of food and collapse on its own. But at this time, the Kuroda army was already surrounded by eyeliner, and the trend of shifting positions was detected by Kato Kiyomasa, so on the way for the vanguard of the Kuroda army to march to Fulai City, Kato's general Iida Naokei and Otomo's important minister Tahara Shonin led the elite troops to ambush successfully, the Kuroda army died more than 300 people, and the 24 generals of Kuroda, Kiriyama Nobuyuki and Kuno Shigetsu were killed one after another, and the remaining more than 1,300 people retreated to the main formation.

The strong attack was weak, the sneak attack failed, Kuroda Rushui was already in a dilemma at the moment, and Kato Kiyomasa and Otomo Yoshinori frequently sent envoys to meet with him, hoping that he would not be confused by the rumors of the Osaka rebels, and immediately surrender his military power, unload his armor and return to the field, otherwise he would launch a general attack on Kuroda's army on 20 April.

Kuroda Rushui Takataka, one of the "two guards in the world", really didn't want to accept this reality, but the rumors in the army have intensified, desertions and arsons have happened from time to time, and at first they could use money as bait to appease these sergeants, but with the exhaustion of money and food, there is no better way to maintain the unity of this temporary patchwork army except to kill a few deserters to stabilize the morale of the army.

In the middle of the night of 20 April, although the deadline had passed, Kato Kiyomasa had given him two days to allow the Kuroda army to remain calm for the time being.

"Heaven is not as good as water, and if water is like water, how can it go against the sky?" The black sky is like water in this formation held a military meeting, and finally decided to surrender to the Toyotomi army, "In the entire Kyushu, only the main family is looking at the wind, it's ridiculous to think about it, it seems that the old man thinks too simply, and the Toyotomi clan should not die." ”

"What about the Shimazu family, the old lord doesn't wait for news from the Shimazu family?" Inoue asked unwillingly.

"With the temperament of the Shimazu family, they are going to send troops early, and now that five days have passed, and there is no news at all, what else do you expect?" Kuroda wiped the military ration in his hand, his eyes were full of reluctance: "It's only eighteen days, heh, is my martial arts like water ending here?" ”