Simple 2000シリーズ Vol. 61: The お姉チャンバラ

Zombie Zone is the European localized name for the first game in the OneeChanbara series. It's a part of the Simple 2000 series by Japanese publisher D3 Publisher, as part of a series of budget priced games that usually sell at 2000¥.

You play as Aya, a scantily clad cowgirl with a scarf, in a hack-and-slash against slow-moving zombies in little arena's. There is a feature called "sword fatigue": if you don't clean your sword in time, it will get stuck in an enemy, giving him an advantage over you. There are also slight RPG elements. You can upgrade your characters by collecting orbs dropped by defeated enemies. At the end of each level, you can use the orbs to make Aya more powerful. Sometimes the enemies drop red orbs; if you collect enough of them, you turn into a demon. Your attacks become more powerful, but they also take away from your health.