OVA
Description
Yuna Roma Seiran is the son of Unato Ema Seiran, Orb Union's Prime Minister following the deaths of leaders Uzumi Nara Athha and Representative Homura. As heir to the influential Seiran family, one of Orb's Five Great Clans, Yuna commands significant political standing.

His family advances a political agenda focused on consolidating power within Orb, contrasting with the nation's traditional ideals of neutrality and coexistence between Naturals and Coordinators. To further this goal, Yuna enters an arranged marriage with Cagalli Yula Athha, Orb's hereditary leader and Uzumi's daughter. Approved by both families, this union is a political maneuver to strengthen Seiran control. During Cagalli's temporary absence, Yuna and his father assume de facto leadership. They align Orb with the Earth Alliance and the extremist Blue Cosmos/Logos organization, discarding Orb's long-standing neutrality and non-aggression principles. This alliance plunges Orb into the Second Bloody Valentine War alongside the Earth Alliance against ZAFT.

Yuna exhibits entitlement and self-importance, frequently blaming military personnel for failures while positioning himself as a strategic authority despite lacking combat experience or tactical acumen. His leadership falters during ZAFT's invasion of Orb, and he reacts with panic and defensiveness to the consequences of his alliances, particularly when dealing with Blue Cosmos leader Lord Djibril.

The arranged marriage culminates in a public ceremony. Kira Yamato, Cagalli's brother, intervenes. Cagalli decisively rejects the marriage, physically assaults Yuna, and orders his arrest for treason, citing his political decisions that endangered Orb. The Orb military and citizens subsequently withdraw support, openly rejecting the Seiran family's authority.

Yuna meets his end during the battle for Orb's capital, Onogoro Island. In panicked flight from the conflict, he is crushed beneath a collapsing GOUF Ignited mobile suit. His death occurs without expressions of grief from Orb's military or populace.