While Oda Nobunaga was preoccupied with the conflicts in the Kinai region, a far larger shadow was slowly approaching on the eastern horizon—that of Takeda Harunobu, known as the "Tiger of Kai," whose tactics and strategies were considered unparalleled in his time.
This powerful ruler of Kai and Shinano harbored ambitions as cold and resolute as the unyielding snow atop Mount Fuji. He not only nibbled away at Shinano but also set his sights on his grand ambition of conquering Kyoto to the west. Through ingenious marriages and alliances, the Takeda clan's influence spread quietly like vines.
Meanwhile, Oda Nobunaga's staunch ally—Matsudaira Motoyasu, who had changed his name to Tokugawa Ieyasu—was also thriving in the Tokaido region. These former partners had once joined forces to divide the Imagawa clan's legacy; however, greed is the eternal poison of any alliance. The brief honeymoon between Takeda and Tokugawa quickly shattered, and war was imminent.
Takeda Harunobu, arrogant and disdainful of his rivals, saw Oda and Tokugawa as nothing more than stumbling blocks on his westward expansion. Meanwhile, in Kyoto, Ashikaga Yoshiaki provided the perfect pretext for his ambitions. This shogun, handpicked by Nobunaga, was no longer content to be a puppet. The humiliation of being forced to bow before Nobunaga had sown seeds of resentment within him. He finally decided to seek a more powerful "protector."
A secret letter traversed the mountains and reached Takeda Harunobu. Yoshiaki's pleas and promises were exactly what Harunobu wanted. He displayed masterful diplomacy, offering Yoshiaki substantial benefits and swiftly adjusting relations with various factions, weaving a vast network centered on restraining Oda Nobunaga. Everything was in place; the tiger of Kai had bared its fangs, ready to advance westward!
Faced with this unprecedentedly powerful enemy, even Oda Nobunaga felt a long-lost chill—a complex emotion mixed with vigilance and a touch of fear. He quickly allied with Tokugawa Ieyasu and even the "God of War," Uesugi Terutora in Echigo, attempting to build an iron wall to block Takeda.
Takeda Harunobu's primary target in his westward advance was Tokugawa Ieyasu, who guarded the Tokaido. This ruthless warlord, known for his patience and strategic brilliance, was about to face the most severe test of his career. Once the war began, the Takeda army's "Wind, Forest, Fire, Mountain" banners were invincible; the Oda-Tokugawa allied forces suffered repeated defeats, and powerful clans around Kyoto surrendered without resistance.
Just as Takeda Harunobu was on the verge of reshaping the political landscape, fate played a cruel trick. Devastating news arrived from the army—Takeda Harunobu had fallen seriously ill! This invincible warlord, ultimately, passed away in frustration and regret for his unfulfilled ambitions.
Upon hearing the news, Oda Nobunaga, in Gifu Castle, must have breathed a long sigh of relief. This turning point, like a divine intervention, eliminated his most powerful enemy. He was able to focus all his energy on the long-restless "puppet" in Kyoto.
Ashikaga Yoshiaki's ambition, after losing Takeda as his patron, did not die; instead, it grew wildly, like a trapped beast. He recklessly issued a proclamation against Oda Nobunaga, frantically contacting daimyo across the land like an ant on a hot plate. However, he lacked the strength and skill to match his ambition.
Nobunaga's counterattack was swift and decisive. After his defeat, Yoshiaki fled in panic to Osaka Castle, under the rule of Hashiba Hideyoshi (later Kinoshita Hideyoshi), ultimately ending his life in disgrace at the age of sixty-one. With his death, the Ashikaga clan's more than two hundred and thirty-year-old shogunate officially collapsed.
The power in Kyoto undeniably fell completely into the hands of Oda Nobunaga. An old era ended with sighs; and a new order, forged by his own hands, was rising amidst the drums of war and the smoke of battle.