In the mirror universe, the free starship Takagi was a Memory Omega jaunt ship in service to the Terran Rebellion, and subsequently the Galactic Commonwealth, in the late 24th century. The Takagi was part of the fleet built by Memory Omega to overthrow the Klingon-Cardassian Alliance. (ST - Mirror Universe novel: Rise Like Lions)
The Takagi was part of the fleet of jaunt ships - battleships with an in-built wormhole generator - Memory Omega built at Erebus Station, beyond the rim of the Milky Way Galaxy. These ships were given to Terran Rebellion personnel after they had received training on the station.
In the year 2378, the Takagi was part of the fleet that jaunted to Bajor to prevent the Klingona from launching a trilithium warhead at B'hava'el. General Miles O'Brien of the Defiant ordered his weapons officer Kirsten Perez to lay down suppressing fire in the no-fly zone between the Takagi and the Defiant. (ST - Mirror Universe novel: Rise Like Lions)
In January 2379, the war was over and the fleet of jaunt ships re-launched with missions of defense and peaceful exploration. In July, Commonwealth Assembly settled on a name for their new, democratic nation, the Galactic Commonwealth. (ST - Mirror Universe novel: Rise Like Lions)