Sengoku Musou 2: Moushouden (Samurai Warriors 2: Xtreme Legends) is extremely late to the Xbox 360 party. Koei released the Samurai Warriors 2 expansion disc on the PlayStation 2 last August in Japan. It was supposed to come to the Xbox Live Marketplace earlier this week, but “operational delays with Xbox Live” prevented it from appearing online. The 2400 Microsoft Point ($30) expansion pack is still coming to the Xbox, but at a later unannounced date. Perhaps it will surface by March 21st to make the European launch date?
If you really need a Samurai Warriors fix a physical copy of Samurai Warriors 2: Xtreme Legends just came out in North America, but only for the PlayStation 2.