The OneChanbara (THE お姉チャンバラ) is a series of action games developed by Tamsoft for D3 Publisher's Simple 2000 series for the PlayStation 2 and later ported on cellular phones, Xbox 360 and Wii. The title is a portmanteau of the Japanese words onee-chan (お姉ちゃん, lit. "big sister", but also a colloquialism for a young adult woman) and chanbara (チャンバラ, "sword fighting"). In 2008, A film based on the game series was released in Japan titled OneChanbara. A straight to DVD film entitled お姉チャンバラ THE MOVIE vorteX was released in 2009.
The hack and slash gameplay involves the player controlling Aya, a Japanese cowgirl in a bikini who wears a scarf and wields a katana. The player is pitted against hordes of zombies and nightmarish boss creatures, who spill torrents of blood when they are attacked. Aya is often accompanied on her adventures by several other warrior women, such as her younger sister Saki, who appears in most titles in the series.
The OneeChanbara series puts players in control of a lone girl (or in later games, two girls with the ability to tag out) against a legion of the undead. Players guide their characters through the stages, completing tasks while hacking through enemies. The player-character's weapon becomes progressively covered in blood, causing their attacks to be slower and to inflict less damage, even getting stuck in enemies if it gets too bad. This is represented by a "Blood Meter" showing how dirty the weapon is. To prevent this, players must actively clean off their sword to keep the blood meter from filling up.
In addition, there is also the "Blood Lust" meter. As a character kills enemies, this meter starts to fill. Once the meter is full, the character will go into a "blood frenzy". This gives the character an increase in attack power, but drains health. To recover from a blood frenzy, the player must use statue items, which are dropped by dead enemies. Additionally each level will contain a large statue. Going to the large statue will remove the blood frenzy and also recover any lost health.
Unlike the stereotypical zombies, most of the undeads encountered in this game series are not automatically killed by decapitation; some would continue to attack even after losing their upper torsoes. This is briefly explained in OneChanbara: Bikini Zombie Slayers by the notion that, while humans killed due to infection with bodily fluid of the undead will be zombified, most undeads are not re-animated corpses but are merely made by some supernatural power that created them to look similar to humans.
Source: Wikipedia, "Simple 2000 Series Vol. 61: The Oneechanbara", available under the CC-BY-SA License.