The Vermillion Knight, Testa-Rossa (緋の騎士 テスタ=ロッサ) is one of the Divine Knights of ancient Erebonian legend in the The Legend of Heroes: Trails of Cold Steel trilogy. However, its name was erased from history and sealed away in the Black Records due to its inflicted curse in the past.
Long ago in S.371, the Vermillion Knight laid hidden underneath the bowels of Valflame Palace until Emperor Hector I encountered it by chance and eventually became its Awakener. They defeated the Dark Dragon, Zoro-Agruga, that had terrorised the capital of Heimdallr with its accursed wrath for over a century. The battle was won but at a heavy cost, as Hector died due to the Dark Dragon's cursed blood and the knight transformed into a catastrophic monstrosity. Eventually it was returned back to its original dormant slumber beneath the capital where nobody could reactivate it again other than the royal bloodline of the Arnor family.
In the Year S.947 in which the War of the Lions took place, Orthros Reise Arnor, otherwise known as the False Emperor, reawakened the "Apocalypse" from its slumber and overpowered all opposition forces against him. Orthros' reign of terror lasted to where not even the remaining princes' forces could stop him, until the appearance of Dreichels Reise Arnor and St. Lianne Sandlot. They finally outmatched it, until Orthros decided to overpower the cursed knight, eventually evolving it the demonic lord known as the Vermillion Apocalypse. It sucked all life from its vicinity, until Dreichels discovered Valimar, the Ashen Knight Orthros was finally defeated, and the cursed knight was eventually sealed again by the newly-throned Emperor Driechels and the Lance Maiden.
On December 26, S.1204., Orthros's descendant, Duke Cayenne, brought Cedric Reise Arnor to the hidden bowels underneath Valflame Palace where Testa-Rossa was sealed. As the Duke brushed off any further warnings coming from Vita Clotilde, Cedric felt a painful throbbing in his chest due to the knight's resonance with his royal blood.
After Crow and Vita's defeat by Class VII, Cayenne furiously hastened his plan and forced Cedric into the dormant knight, thus the Vermillion Apocalypse was reawakened from its slumber once again.
- Its name and features became a conceptual reference for the Red Constellation's crimson features.