List of Gurren Lagann Characters - Rossiu Adai

Voiced by: Mitsuki Saiga (Japanese), Johnny Yong Bosch, Michael McConnohie (epilogue) (English)

Rossiu Adai (ロシウ・アダイ, Roshiu Adai?) is one of the main characters of the anime and manga series, Tengen Toppa Gurren-Lagann. A boy from another underground village, Adai, in which the people worship the Gunmen as gods. A modest but intelligent person, he's the apprentice of his father, the village elder who governs Adai and performs its ritualistic method of dealing with over population by having people draw sticks with the winners sent up to the surface to die, Rossiu's mother being among those chosen. But when Gimmy and Darry were selected to leave the village, Rossiu is horrified to learn his father rigged it as they are orphans and decides to go with the twins and, thus joining Team Gurren. Before he leaves, the village elder gives him a book that seems to withhold some secrets from humanity's past, with the task to find someone able to read it, as no one in his village can decipher its contents. After Kamina's death, Rossiu temporarily begins piloting Gurren in his place, though initially has trouble, due to Simon's breakdown.

After the end of the war, Rossiu became Simon's second-in-command, always trying to make him act more serious about his duties as the ruler of Kamina City. However, in spite of his time with Team Dai-Gurren, Rossiu became a lot like his father and took Lordgenome's last words seriously, leading a secret project to access Lordgenome's memories and learn the history behind him and the Anti-Spirals. However, when the Anti-Spiralized Nia causes a riot across the city, with an angry mob formed against Team Dai-Gurren, Rossiu decides to use Simon as a scapegoat and overthrows him. Though he was the one who placed him in prison with the death penalty, keeping up a cold heartless facade in public, Rossiu lamented his actions in secret from all except Kinon. From there, Rossiu and his subordinates prepared a contingency plan by having the rest of the people to take shelter in the underground villages, assumed to be safe by the government, with a select few to board the escavated Arc-Gurren. However, when Leeron showed him that no life form, in the surface or underground, would survive the impact, which would render the planet completely uninhabitable for one year, Rossiu decided to change his plans, by filling the rest with animals and livestock, ensuring a chance of survival of them, and abandoning the rest of mankind. Earth was then attacked earlier than expected, and he had to escape with only half the expected refugees on board of the Arc-Gurren.

However, Rossiu's plans were once again foiled by the Anti-Spirals who had already set a large force awaiting to ambush the Arc-Gurren in space. Just when he was about to lose hope, Simon and the rest of Team Dai-Gurren came to his aid. One week after the Human Extermination System was stopped, Rossiu left a farewell message and set for Adai where he intended to commit suicide after settling things with his father. However, Kinon found the message and Simon rushed with her in Gurren Lagann to stop him, with Simon beating some sense into him and giving Rossiu the strength to keep living. Rossiu takes the duty of watching out for Kamina City, while Simon and the rest of Team Dai-Gurren depart from Earth to the Anti-Spirals' homeworld, having Kinon and Guinble assist him. After the final battle against the Anti-Spirals, Rossiu was the priest for Simon and Nia's wedding, and in the epilogue, he is seen still holding the position of commander-in-chief, as Simon did not reclaim it.

The name that Kamina refers to him as in the primary series "dekosuke" is a remark regarding the large size of Rossiu's forehead. The name "dekosuke" roughly means "big forehead". In the dub, Kamina nicknames him "Forehead Boy."