Joji Nakata as Uesugi Kenshin and Tokugawa Ieyasu; in fact, Nakata uses an exceptionally close tone of voice for both, but the difference can be determined via the volume of their respective dialogue - Kenshin is soft-spoken, whereas Ieyasu is emotional and gruff.
Mariko Suzuki voices both the sultry Nō and Tomboyish Kai.
Dueling Games: With Sengoku Basara; while Samurai Warriors features less over-the-top personalities, but more grounded historical fiction aspects compared to the former, it has better international appeal and marketing. Koei Tecmo makes it more clear this franchise is geared for all audiences. Meanwhile, Capcom and Sengoku Basara (at least in the latest installments) likes to target itself with the Yaoi fandom - this is shown with how this series likes to insert its fair share of women, whereas Sengoku Basara piles on the Ho Yay moreso than Samurai Warriors.
To make this more apparent, both series has a pseudo "competition" of sorts with one another with regards to new character inclusions: if there's a historical figure in the Jidai Geki added in a new installment of one series first, chances are the other series will add their own rendition of the individual for their next installment (and vice versa). For example, Yoshihiro was part of the Sengoku Basara roster in its first game before the character made his debut in Samurai Warriors 2; likewise, Hanbei was added to the Samurai Warriors 3 cast following his appearance in Sengoku Basara 2.
Furthermore, Samurai Warriors started to use particular character "archetypes" Sengoku Basara used first for their cast: take Gracia, for instance - she's meant to be the "Christian" representative of Samurai Warriors when Pontiff Xavi pulled this schtick originally in Sengoku Basara (until he was replaced by Ootomo Sourin). Meanwhile, characters like Hojo Ujiyasu and Kobayakawa Takakage are the "representatives" of their respective clans in Samurai Warriors in contrast to Sengoku Basara using Hojo Ujimasa and Kobayakawa Hideaki.
Spin-OffSamurai Warriors: Spirit of Sanada is meant to be Koei Tecmo's answer to Capcom's Sengoku Basara: Sanada Yukimura-den, capitalizing on the popularity of the NHK television drama Sanada-Maru. However, Koei Tecmo seems to be ahead in the race for this particular installment as they added more content in response to Capcom's less-than-stellar rhetoric for Yukimura-den, such as a revamped campaign system, aging up characters appropriately as the story progresses ("old Yukimura" has a different moveset than when he is a young adult), a new female character (Chacha), adding a popular historical figure that has been in Sengoku Basara (Sasuke), and of course, a localized release.
Fan Nickname: "Pedo-yoshi" for Hideyoshi due to his interactions with Chachanote His historical concubine and his son's Toyotomi Hideyori's mother in Samurai Warriors: Spirit of Sanada; historically, Hideyoshi was roughly 33-years older than her.
Daisuke Gori voiced Shingen Takeda, but his sudden passing gave Ryuzaburo Otomo the role starting from Samurai Warriors 3: Xtreme Legends.
The original voice actor for Hideyoshi in the first game and Xtreme Legends expansion was Munehiro Tokida, but was mysteriously replaced by Hideo Ishikawa permanently when Samurai Warriors 2 was released. Likewiwse, Takayuki Sasada voiced Azai Nagasama in the first game, until Hiroshi Kamiya was brought in to replace him after becoming a playable character in Samurai Warriors 2.
Playing Against Type: It's practically unthinkable to hear Nobuyuki Hiyama not voice a character without him going Hot-Blooded with loads of Large Ham, yet his portrayal of the calculating, chaos-loving Fuuma Kotarou absolute sells it to players.
Gina Bowes voiced Kunoichi in the first game; due to the character's removal in Samurai Warriors 2, she returns in Samurai Warriors 3, making her the only English voice actor for this series to return for not only another game, but the exact same role.