He always coolly stands by his master Yukimura and aids him whenever possible. He made a rivalry with Kasuga, a ninja in service to Uesugi Kenshin, an enemy of Shingen.
After Toyotomi Hideyoshi died, Shingen fell ill and Yukimura took control over the Takeda army. Sasuke kept aiding Yukimura, even when he had to make terrible decisions. In the anime Sasuke has a crush on Kasuga and even in the game he has but refuses to reveal to her his true hidden feelings. [Source: wikia]
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