In November, after repairing, the Yuan army collected enough food and grass for the march in Kyushu, and replenished the ammunition of the fleet from Goryeo, and after all preparations were made, they set out by ship on the 20th to attack the island of Shikoku.

In order to prevent the attack of the Yuan army, under the strict orders of the shogunate, the Japanese samurai built a large number of stone fortresses called "Yuankou fortifications" along the coast and guarded them behind the forts. After the Yuan fleet arrived at the Uwa coast of Shikoku, it discovered this situation, and first concentrated the artillery on the warship to bombard the stone fortress, due to the ferocity of the Yuan army's artillery fire, the stone fortress was mostly broken, and the Japanese samurai guarding the stone fortress suffered heavy casualties, seeing the Yuan army landing, the Japanese samurai troops launched a charge against the Yuan army, but soon fell under the dense rain of arrows fired by the Yuan army. After two days of fighting, the "Yuankou Fortification" painstakingly built by the Japanese was broken through by the Yuan army, and most of the defenders were annihilated, and only a few escaped.

At the same time as attacking Uwa, another Yuan fleet sailed into Tosa Bay, and after the Yuan army landed, it conquered Kochi Castle, and then joined forces with the Yuan army that came from Uwa, swept away the Japanese army, and seven days later, the Yuan army successfully occupied the entire territory of Shikoku Island.

After the occupation of Shikoku, Xindu continued to launch an offensive non-stop, and he was determined not to give the Japanese a chance to breathe, so he led the Yuan army fleet to Osaka Bay, and after capturing Osaka, he took Kyoto.

Hojo Tokimune judged the direction of the Yuan army's attack, and urgently summoned the imperial family from all over the country to Osaka to help defend it, and the samurai from all over the country rushed to Osaka day and night after receiving the order, and the number of about 50,000 people was unprecedented, but by the time these samurai arrived in Osaka, Osaka had already fallen. It turned out that after learning that the Mongols would massacre the city that did not surrender, the merchants of Osaka did not want to destroy this prosperous commercial city, led by several major families, secretly contacted the Yuan army, expressed their willingness to surrender and protect the city, and Xin Du agreed to the request of the merchants of Osaka to promise not to slaughter the city, not to plunder, and to protect the lives and property of the residents in the city. Therefore, the armed forces of the merchants of Osaka secretly opened the city gate, received the Yuan army into the city, and killed about 7,000 Japanese samurai troops defending the city, which was the "Osaka bloodless opening of the city" incident.

After the Yuan army entered Osaka, Xin Du fulfilled his promise, did not commit any offense to the residents of the city, and collected grain and materials to "give it its value", and was called "Buddhist soldiers". Some Japanese samurai who were unwilling to surrender launched a suicidal attack on the Yuan army, and most of them were killed, and Osaka Castle Keeper Kusai Tomocho and his 32 men retreated into the Buddhist temple after being defeated, and committed suicide by seppuku.

After the fall of Osaka, Japanese samurai gathered in Kyoto to join the city defenders, and the number of Japanese samurai who arrived one after another, together with the original defenders of Kyoto, soon exceeded 100,000. The ruling Hojo Tokimune also personally went to Kyoto to command the defense, and swore a bloody oath to annihilate the Yuan army in Kyoto.

Taking advantage of the confrontation with the Yuan army, the Kamakura shogunate once again strengthened its power. On December 8, the shogunate ordered the rice produced by the national government and the Honsho Ichien to be used as military supplies for the war, and the earlier order that the officers and soldiers of the temple shrine and the main office that the officers and soldiers loyal to the imperial court must participate in the war against the Yuan under the command of the samurai were also officially recognized by the imperial court. As a result, the power of the War of Resistance held by the Imperial Minister, who had been appointed by the Imperial Court, was completely replaced by the samurai regime, and the only thing the Imperial Court could do was to hold prayers for the surrender of the enemy at the shrines and Kokubunji Temples in various countries. The power of the samurai shogunate has since surpassed that of the public court and has since become the sole ruler of the Japanese archipelago.

At this time, although the number of Japanese troops greatly exceeded that of the Yuan army, how to command these samurai, who were not subordinate to each other in peacetime, to fight together became a difficult problem for the Kamakura shogunate. And the Yuan army did not give the shogunate time to solve the problem.

Xindu first sent an archery book into Kyoto, ordering the Japanese army and civilians to surrender, so that they could avoid the slaughter of the city and protect the Japanese court according to Osaka's example. Hojo Tokimune refused, and also let people shoot into the Yuan camp with an arrow book, writing "Those who descend will not die", and then led the army out of the city and went straight to the Yuan camp.

Hojo Tokimune led about 50,000 Japanese samurai troops, about 5,000 cavalry, and the rest were foot soldiers. The Yuan army still used artillery to bombard the Japanese first, followed by crossbow arrows, and then attacked with cavalry. The Japanese army was killed and wounded under the fierce artillery bombardment of the Yuan army, and most of the Japanese samurai who rushed close also shot crossbow arrows into hedgehogs, although the Japanese samurai had excellent knives, but in addition to some generals with good armor protection, most of the lower-level samurai only had simple armor, so they suffered heavy casualties, and the 50,000 army quickly collapsed under the attack of the Yuan army, and Hojo Tokimune was also injured by the Yuan army's artillery fire in the battle, "the iron sheet hole its armor, and the shoulders and arms were worn", the blood dyed his armor red, and the cavalry of the Yuan army saw that his armor was bright, and knew that he was a general, They swarmed to capture him, but at the last moment, a samurai named Takesaki Kicho arrived on horseback and dragged Hojo Tokimune out of the battle area, so as to avoid being captured by the Yuan army.

Hojo Tokimune led the remnants of his army to retreat into Kyoto and defend the castle. After defeating the Japanese army, the Yuan army did not rush to attack the city, but pursued the scattered Japanese samurai, and killed them all, for a time the corpses under the city of Kyoto were like a mountain, and the Hojo Tokimune, who went to the city to look at the enemy's situation, saw this, was angry, spurted blood, fainted, and then woke up for the imperial doctor sent by the emperor.

After completely eliminating the Japanese army outside the city, the Yuan army began to attack the city, and unlike in the past, the Yuan army did not forcibly erect a ladder to climb the city, but concentrated artillery to bombard the city. The Japanese on the city wall were stunned to find that a huge cannon had been erected in the array of the Yuan army.

What the Japanese didn't know was that this cannon was not cast by the Mongols, but by craftsmen of the Song Dynasty, and it had a special name: "Xiangyang Divine Cannon".

The artifact of the Song people, which had dealt a heavy blow to the Mongols in the Battle of Xiangfan, now appeared in the array of the Yuan army. This cannon, along with its ammunition, was secretly bought by the Mongols from the Song people at a high price, and originally Kublai Khan planned to study it well and copy it, but after learning about the military situation on the Japanese front, Kublai Khan sent someone to transport it to Xindu by ship to "help it succeed." ”

After the occupation of Kyushu, this cannon came to Japan with the fleet transporting grain, grass and ordnance, but because it was huge and bulky, it was difficult to move, and Xindu did not intend to use it at first, from the occupation of Kyushu to the attack on Shikoku Island, it was always placed on the ship, until the Battle of Kyoto, seeing the tall and strong walls of Kyoto, Xindu remembered it and ordered someone to unload it from the ship and transport it to the front line in Kyoto.