<s>
,	O
initially	O
defined	O
,	O
is	O
a	O
series	O
of	O
action-adventure	O
hack	B-Application
and	I-Application
slash	I-Application
video	I-Application
games	I-Application
originally	O
developed	O
by	O
Tamsoft	O
for	O
D3	O
Publisher	O
's	O
Simple	O
2000	O
series	O
.	O
</s>
<s>
The	O
series	O
centers	O
around	O
Aya	O
,	O
a	O
cowgirl	O
who	O
wears	O
a	O
scarf	O
and	O
wields	O
a	O
katana	B-Operating_System
,	O
who	O
is	O
pitted	O
against	O
hordes	O
of	O
zombies	B-Application
and	O
other	O
monsters	O
.	O
</s>
