Ogata Koan (1810-1863) was born to a retainer of Ashimori Domain in Bitchu Province. After studying Dutch learning under Tsuboi Shindo in Edo, he opened his own academy in Osaka's Kawaramachi in 1838. In 1845 he purchased a merchant house in Kashosho (now Kitahama 3-chome) and relocated the academy there, running it for eighteen years while dedicating himself to medical and Dutch-learning education. A pioneer of smallpox vaccination in Japan, he wrote Korori Chijun during the 1858 Osaka cholera epidemic to spread effective treatment — earning him the epithet "father of Japanese public health." In 1862 the shogunate summoned him to Edo as senior physician and head of the Western Medicine Institute, but he died suddenly the next year. The more than 1,000 students who passed through Tekijuku became the human foundation of modern Japan.

Fukuzawa Yukichi entered Tekijuku at age 22 in 1855, studying under Ogata Koan. He briefly returned to Nakatsu after his brother's death but soon rejoined; by 1857 he had become head student (jukucho), leading translation and study of Dutch texts. His autobiography Fukuo Jiden vividly depicts the academy's fierce study life: "We pored over the Doeff dictionary through the night in the Doeff Room, and when exhausted used the dictionary itself as a pillow"; "We devoured Dutch books through hunger and cold." In 1858 he was summoned to the Nakatsu Domain residence in Edo as a Dutch-learning instructor — the origin of what would become Keio University. The study ethos of Tekijuku fostered the philosophy of "independence and self-respect" that shaped modern Japanese education.

Omura Masujiro (1824-1869) was born to a village physician in Suo, Choshu. He entered Tekijuku in 1853 and rose to become head student, studying Dutch learning, medicine, and military science under Ogata Koan, absorbing modern military knowledge through Chinese translations of Dutch texts. He served Uwajima Domain, the shogunate, and Choshu in turn, and during the Boshin War commanded the imperial army to victory at Ueno against the Shogitai and led the Aizu campaign. Appointed Senior Vice-Minister of the Military in 1869, he laid the foundations of the modern Japanese army — but was gravely wounded in an attack at Kyoto's Kiyamachi in September and died that November. He is remembered as the "father of the Imperial Japanese Army" and a pioneer of industrial modernization. The Dutch-learning scholarship and logical rigor he gained at Tekijuku made the reform of Japan's military possible.