Nobukata served under both Takeda Nobutora and Takeda Shingen and also was tasked with young Shingen. In 1541 Nobutora, along with Amari Torayasu, was driven out from the position of the head of Takeda clan, and he served as the general for Shingen often leading the troops into a battle when Shingen could not. In 1542, he would personally finish off Takato Yoritsugu at Ankokuji, shortly after the Siege of Fukuyo. In 1545, he successfully captured Takato castle. In 1546, he defeated Uesugi Norimasa at Usui Toge. With these victories, he was instrumental in gaining the control of Shinano Province and proved himself a skilled tactician. He was known as one of the "Twenty-Four Generals of Takeda Shingen".
After these victories, Nobukata increasingly became selfish and started to hold victory ceremonies without firmly winning a battle. These victories rapidly became fewer. As Nobukata was the eldest of the Takeda retainers and having educated Shingen, few could criticize his actions. In 1547, Nobukata and his troops were almost completely wiped out in a battle against the Murakami clan and without a timely rescue by Hara Toratane, Nobukata himself would have been in danger as well. Shingen offered the following waka to Nobukata to encourage him to correct his act.
- Dare mo Miyo Mitsureba Yagate Kaku Tsuki no Izayofu Ana ya Hito no Yo no Naka
- 誰もみよ 満つればやがて 欠く月の 十六夜ふ穴や 人の世の中
- (Translation) "Everyone sees that even a beautiful full moon starts to change its shape, becoming smaller as the time passes. Even in our human lives, things are as it is."
In 1548 at the Battle of Uedahara, Nobutaka, satisfied with a victory, had his troops stand down to hold a ceremony. Murakami's troop regrouped and counterattacked, killing Nobutaka and Amari Torayasu.
The Meiji era politician Itagaki Taisuke was Nobukata's direct descendant, 12 generations removed.
In NHK's 2007 Taiga drama Fūrinkazan, Itagaki is played by Sonny Chiba. Like in the novel it was adapted from, Nobukata was portrayed more heroically, supposedly the one who was trying to rein in the young Takeda Harunobu (Shingen) from his arrogance and chose to sacrifice himself so that Harunobu may survive the Battle of Uedahara.