Just one day after her main event victory in Pancrase, Mei “V.V” Yamaguchi has been announced for the promotion’s next event, Impressive Tour 4, on May 3rd. The reigning Valkyrie Featherweight Champion will face eight-year mixed martial arts veteran Akiko “Betiko” Naito in a featured matchup.

The fighters are both coming off of competitive bouts with noted Japanese striker “Windy” Tomomi Sunaba, and both fought to Majority Decisions after two rounds. Naito came up just short against Sunaba last December, while Yamaguchi picked up a close victory this weekend in a spirited bout.

Yamaguchi (7-2-1) recently underwent significant changes in her MMA career, as she first dropped her former “V Hajime” ring name and then left her long-time jiu-jitsu academy to become a freelance fighter. The changes appear to have thus far paid off, as Yamaguchi was impressive in her battle with Sunaba on Sunday. Controlling much of the opening round on the ground with strikes and submission attempts, Yamaguchi then fought through a tougher second round and came out with her first victory of 2011 in a Fight of the Night bout. It marked the first time that a women’s fight had headlined a Pancrase card.

With the future of Valkyrie still uncertain, Yamaguchi has taken the opportunity to expand into Pancrase and will now make her second appearance for the promotion in May.

Naito (6-10-0) made her pro debut on May 22, 2003 and went 4-4 in her first eight fights over the course of two years. She has competed sparingly since mid-2005, however, and has struggled in recent fights for a variety of promotions. Having won just twice in her last six bouts, with both wins over Yasuko Mogi, Naito will come into the fight with Yamaguchi as a significant underdog, but she put on a game showing in her December battle against Sunaba and an upset is not entirely out of the question. Naito has only been stopped three times in 16 career bouts, and her best chance for victory is via decision.

Pancrase Impressive Tour 4 takes place on May 3rd at Differ Ariake in Tokyo, Japan. The promotion currently lists the bout between Yamaguchi and Naito as the main event, and it may therefore serve as the second consecutive female headliner in Pancrase.

Updated at 10:15 A.M. Pacific time with additional information on possible main event status.