Armored Core: Project Phantasma

The Raven receives a cryptic message: infiltrate the underground complex known as Amber Crown, and an extremely lucrative reward is waiting. Inside, they meet Sumika Juutilainen — an escapee from the Doomsday Organization, the shadow group that operates within the complex. Sumika becomes both client and partner. As the missions continue, a rivalry develops with Stinger, a fellow pilot in the Doomsday Organization's employ who grows more dangerous as the truth of Amber Crown is uncovered. That truth culminates in Project Phantasma — a top-secret weapon system developed using Sumika and Stinger as test subjects. Stinger, determined to claim that power for himself, merges with the Phantasma weapon. The Raven defeats him and dismantles the project, ending the Doomsday Organization's operation.