Tomache Massarik, also known as Tomáš Masaryk, hails from Hiland, an orbital energy satellite station where his father Batstraff worked as a laborer. During the Zanscare Empire's invasion, Tomache, his brother Karel, and their friends Elischa Klánský and Martina Klánský fell captive to BESPA forces. Liberated by Üso Ewin, Marbet Fingerhat, Warren Trace, and Odelo Henrik of the League Militaire, this rescue spurred him to join their resistance.

As a 17-year-old League Militaire cadet, Tomache first served in a support role aboard the transport vessel *White Ark*. He later transitioned to frontline combat, piloting Victory Gundam variants alongside Üso and Odelo on critical missions against Zanscare operations. These assignments were conducted under League leadership, including Captain Jinn Geneham of the *Reinforce Junior*.

Tomache possesses black hair cut to ear length, blue eyes, and a medium complexion, typically dressed in practical attire like a coat and turtleneck. His ultimate fate remains unresolved after the Zanscare War's final battle; he is absent from the series' concluding scenes without explicit confirmation of survival or death. Supplementary materials suggest he likely survived the conflict despite his epilogue absence.

The character's name references Tomáš Garrigue Masaryk, the first president of Czechoslovakia.