Google Play Store has accidentally leaked the Legendary Hero set to join Fire Emblem Heroes this month, and it is Roy from Fire Emblem: Binding Blade, with the title Blazing Lion. [Thanks, ThatOneGuyElijah on Reddit!]
March is set to have new units from The Binding Blade, and Roy as the Legendary hero fits in with his allies. The Legendary focus banner for February is set to start on February 26 and end on March 5, 2019.
Fire Emblem Heroes is available for iOS and Android.