Aileen is a new unit introduced in Metal Slug Attack.
She was a member of the Amadeus syndicate but she joined up with the pirates because she couldn't stand military discipline, and wanted more freedom to act on her own.
She keeps enjoying alcohol and sometimes drinks too much, even during the middle of a battle. However, her equipment has been customized so that even drunk her ability will not be impeded. Because she aims to collect beautiful objects, she's off traveling the world in order to find rare gemstones.
First appearing in the Extra Ops "Break in the Shell", the Ptolemaics use the Emerald Turtle to find gemstones in the sand. Aileen hears of this and sets off with several pirates to steal the gems for herself. Upon arriving, she destroys the Emerald Turtle and claims the gemstones as her own.
- Aileen is the only limited Box Crank unit that doesn't use box items.
- She is the second Box Crank unit to have a Special Rare version. The First being was Navy.