The protagonist of Growlanser V. Having lost his parents at a young age, he was an orphan brought up in Warslee village which the Peace Maintenance Brigade founded. By nature he has good fighting ability well-known in the neighborhood. He was to be enlisted into the Peace Maintenance Brigade at age 20, but Screapers attacked and destroyed his home and he suffered life-threatening injuries. To save his life, he received a surgical operation which gave him some abilities, one of which is to activate an ultrasonic barrier which weakens Screapers.
He was assigned to the PMB Operations Division under Melvina. As a new member he met Krious, Fanille, and a number of other important persons; together they handle missions and duties. They deal with the issues between the countries and events that brew up.
Thus in his journey he became aware of his personal history and secret about his body. He had special cells implanted in his body, which were a fusion of human and Screaper cells, called the Zero Cell (or #1 Cell). He had to take medication regularly or else his life would be at risk. He and his party found out that the medication was made from energy extracted from humans. Disgusted at this, Krious had him go through a "time sealing" technique (the same used on Ziekwalt) until Fanille could find a cure. This magic was performed by the Pothrad Pernagi. Zeonsilt wouldn't have to take vital energy supplements to live and he wouldn't be in danger of turning into a Screaper any more. With this, the fairy Korin had to stay by his side to preserve it. and he. After this he and his party defeated Ziekwalt and the Queen Screaper, and he continued working for peace.
When he was younger he was raised by a lady in Warslee, and she left behind a letter for him. She raised Zeonsilt for seventeen years and was going to tell him the truth about his parents when he became twenty years old. She didn't know about his father, but as for his mother, her name was Romina and she joined the Peace Maintenance Brigade to fight Screapers, and didn't return home. Romina left Zeonsilt behind, and the foster mother took him in and moved to Warslee. She said that perhaps because he didn't receive affection from his parents, he had a cold air about him. She loved him like her real child. She became ill and died. Romina died when Zeonsilt was not yet one year old. Zeonsilt's father was the Red Justice Ranger, close friend of Randall.
Shuweizer traveled into the past and killed Zeonsilt, however Merklich's party went to that point in the past with Yurii's help to rescue him. When Merklich's party came to the Peace Maintenance Brigade a second time to request their help in destroying the Dragon Abyss Towers, Krious ordered as an S-Class mission to Zeonsilt to help them defeat Screapers. Fanille had been endeavoring on finding a cure for Zeonsilt's body, and with Merklich's help she was successful. He continued to accompany and help Merklich until Infinitor was defeated and history was changed.