Ruben is a tall man with a long, brown hair. Most of his hair is gathered into ponytail while two tufts on either side of his head are combed up into points. His sideburns are darker brown.
After the Crimson Lion squad places fifth in the squad rankings, Ruben and the others are berated by their new captain, Mereoleona Vermillion, and she forces the squad to undergo training at the Ultime-Volcano Mountain Trail. Having reached the summit before sundown, Ruben is allowed to bathe in the hot springs.
A week later, Ruben attends the Royal Knights Selection Exam and is placed on Team I with X and Nils Ragus. Before their first match, Ruben and Nils question who X is, so Rill drops his disguise. During their first match, Ruben and Nils destroy the crystal after Rill defeats their opponents. Afterwards they have to drag the captain who is distracted and critiquing his painting.
During their second match, Ruben and Nils decide just to support Rill. The pair panic when faced with Team K's Compound Magic, but Rill is able to redirect the Thunder Arrow and destroy Team K's crystal.
Several days after the exam, Ruben and the others selected to be Royal Knights all assemble in the Royal Capital and are placed under the command of Mereoleona. After the squad change into their new robes, Mereoleona introduces additional members and reveals the location of the Eye of the Midnight Sun's base. After the squad travels to the Gravito Rock Zone, Mereoleona explains the situation and divides the squad into teams. Rill infiltrates the dungeon with Ruben, Fragil Tormenta, and Puli Angel.
As light shines out from the dungeon, Ruben and his team begin glowing themselves and are possessed by elf spirits. Rossa possesses Ruben, and the team follows Lira after he crashes through the floor. Later that night, all the remaining elves are exorcised after William Vangeance and Licht combine their magic to connect the elves to a giant tree through which Asta sends Anti Magic.
- The Hot Spring Training Camp
- Royal Knights Selection Exam
- Attacking the Eye of the Midnight Sun Base