Tokyo Mirage Sessions FE crosses Fire Emblem with which Atlus series?

Tokyo Mirage Sessions ♯FE crosses Fire Emblem with Atlus's Shin Megami Tensei series.

The game was developed by Atlus and published by Nintendo, combining the two properties in a modern Tokyo role-playing adventure. Its story follows teenagers connected to Fortuna Entertainment who battle hostile Mirages and become Mirage Masters alongside friendly beings based on Fire Emblem characters.

The crossover was first announced in 2013 under the working title Shin Megami Tensei X Fire Emblem. Rather than using traditional Fire Emblem grid-based battles, it uses a turn-based system influenced by Shin Megami Tensei, including weaknesses, skills, and chain attacks. The cast and setting are original, with locations such as Shibuya and Harajuku serving as major backdrops.

Persona is an easy wrong answer because it is another Atlus series and the game has stylish urban characters, music, and supernatural themes. However, Persona is not the series named in the crossover's title or core premise. Tokyo Mirage Sessions ♯FE is specifically a Shin Megami Tensei–Fire Emblem collaboration, even though its presentation also resembles Persona in places.