By June 17, 1716, the seventh shogun of the Tokugawa dynasty was dying. Tokugawa Ietsugu (徳川家継, Tokugawa Ietsugu) had been born on August 8, 1709, and had become shogun at the age of three following the death of his father, Tokugawa Ienobu (徳川家宣, Tokugawa Ienobu). He was six years old. The cause was a cold — a respiratory illness that his small body could not overcome. He would die on June 19, 1716. He had held the most powerful office in Japan for his entire conscious life and exercised none of its power.

Ietsugu's death ended the direct male line descending from the third shogun, Tokugawa Iemitsu (徳川家光, Tokugawa Iemitsu) — the line that had held the shogunate since 1623. Through his brief reign and his father's before it, real authority had rested with the Confucian scholar Arai Hakuseki (新井白石, Arai Hakuseki) and chamberlain Manabe Akifusa (間部詮房, Manabe Akifusa). The so-called Shotoku Reforms (正徳の治, Shotoku no Chi) — emphasizing Confucian ethics, court ceremony, and fiscal restraint — bore Hakuseki's stamp far more than the child's. Now both the shogun and the administrative framework built around him were finished.

The senior council of elders, the roju (老中, roju), faced an unprecedented problem. The most powerful hereditary office in the country had no natural heir. The Owari (尾張, Owari) branch of the Tokugawa family held the most obvious claim by proximity and precedent. But according to accounts, the council was drawn toward a different candidate: Tokugawa Yoshimune (徳川吉宗, Tokugawa Yoshimune), lord of the Kishu (紀州, Kishu) domain and head of one of the three Tokugawa cadet houses.

Yoshimune was, by the standards of Edo's elaborate court culture, an eccentric. He loved falconry — the austere hills, the patience required, the discipline of a trained bird — and his governing style matched the hobby: lean, precise, and unsentimental. He was known to disguise himself in plain clothes and walk through markets and neighborhoods, listening to what ordinary people said about their lives, their costs, their complaints. In a world built on ritual distance between rulers and ruled, this was considered strange. It was also considered effective. As daimyo (大名, daimyo) of Kishu, he had already introduced local reforms that stabilized the domain's finances and demonstrated what careful, pragmatic governance could accomplish.

Yoshimune was 31 years old — Western calculation — when the roju chose him as the eighth shogun. He would turn 32 in November. Arai Hakuseki, who had shaped policy through two child shoguns and over a decade of court influence, was dismissed almost immediately upon Yoshimune's arrival in Edo (江戸, Edo). The scholar who had guided Japan was simply out. Yoshimune was not interested in inheriting a system of administrators; he intended to govern himself.

The Kyoho Reforms (享保の改革, Kyoho no Kaikaku), launched beginning in 1722, would become the defining achievement of his reign. He relaxed the sankin-kotai (参勤交代, sankin-kotai) alternate attendance requirements that kept daimyo permanently impoverished and away from their domains. He cracked down on merchant wealth and luxury. He promoted agricultural development and introduced merit-based stipends in place of purely hereditary ones. He ordered a large globe made and imported a telescope from the Netherlands — in a country that had maintained an official policy of isolation from Western knowledge for generations. In 1720 he lifted the ban on Western books, seeding the growth of rangaku (蘭学, rangaku), Dutch studies, that would eventually give Meiji reformers the scientific and technical foundation to modernize Japan in a single generation.

He ruled as eighth shogun from 1716 to 1745 — one of the longest and most consequential reigns in Tokugawa history. The shogunate he inherited had been drifting under the guidance of scholars and ceremonial administrators. The shogunate he passed on was reformed, financially stabilized, and pointed — however cautiously — toward the wider world. All of it set in motion because a six-year-old child caught a cold he could not survive.