Ahmos Gale with Graimkaiser or Julia Asuka with Bloodykaiser
For Gale, in Stage 3, Eiji must convince with him. In Stage 4, agree the choice (1st choice). After Stage 10, pick Archangel's route. Finally, in Stage 14, have a battle encounter between Eiji & Gale.
For Julia, in Stage 20, Eiji must convince "???". In Stage 27 & Stage 35, don't destroy Bloodykaiser.
You can pick one of them only after Stage 39. If you have Gale in your team, you won't have Julia even you have the requirement to recruit her.