Otani became Hideyoshi's retainer throngh the good offices of Mitsunari Ishida. A favorite with Hideyoshi, he received a part of Hideyoshi's name (yoshi) and changed his name to Yoshitsugu and later to Yoshitaka. Yoshitaka was promoted to Lord of Tsuruga in Echizen Province (Fukui Prefecture), with 50,000 lcoku.
Then Otani was appointed a Jumor Judge (1585), and later promoted to a magistrate. Resigned after he became blind due to leprosy. After Hideyoshi died, Yoshitaka was friendly to Ieyasu Tokugawa but their relations cooled and Yoshitaka returned to Tsuruga.
When Ieyasu attacked Kagekatsu Uesugi Yoshitaka followed Ieyasu and advised Mitsunari to side with Ieyasu. Mitsunari, on the contrary, revealed to Yoshitaka his plan of attacking Ieyasu. Yoshitaka re peatedly tried to dissuade Mitsunari from carrying out the plan. As Mitsunari would not change his mind, Yoshitaka sided with Mitsunari. In the Sekigahara Battle (1600), he led his troops on a palanquin and fought bravely together with Hideaki Kohayagawa and Yasuharu Wakisaka. Defeated, he killed himself.