Rook is noted to have an extremely handsome appearance, with feminine-looking features and striking silver hair. The only detail that Rook changed during the creation of his avatar was the colour of his hair.
The child of a detective and a thief, Lucius was trained by both his parents in their disciplines from a young age and displayed exceptional talent in both.
Unfortunately, soon after his 15th birthday, Lucius's parents were killed in a plane crash after they risked their lives getting children to safety.
After inheriting their estate, Lucius realized that he had no idea what path to take in his life. While going through his father's belongings, he found the headset for Infinite Dendrogram and correspondence indicating his father had been asked to investigate the game. Lucius decided to start playing himself to find out what to do in his life.
As the sub owner of the Death Period, his influence in the clan is second only to the owner.
Lord Luxuria (色欲魔王): A Superior Job of no grouping from the Demon Lord series that specializes in transforming monsters into a Kin.
- Progress (存在昇華): An active skill that can transform a creature in the user's minion capacity into a Kin, a unique lifeform with the ability of both a human and a monster. However, the possibility of success is 1% and the target will die if it fails.
- Neoteny (制限昇華): An active skill that transforms the target into a Kin temporarily. Unless the target is completely untalented, the skill will not fail, however, it costs 10 job levels per minute.
- The End of Lust (色欲の終焉): The "Final Blow" of the Lord Luxuria. It can transform the target into a Kin permanently with a 100% chance of success. The degree of enhancement is far stronger than Progress and Neoteny, however, the user and all creatures other than the target that are or have ever been in their minion capacity (including other Kin of the previous job holder) will die.
Lost Heart (亡八): The high-rank job from the Pimp grouping. It had three conditions to achieve this job: having reached level 50 as a Pimp, the sum total stats of all underlings being above a certain point, and at least 1,000,000 lir earned through Pimp work.
Pimp (女衒): A low-rank job. It has high minion capacity. The status growth of this job focuses on MP and SP.
- Male Temptation (雄性の誘惑): An active skill that applies the Charm debuff to female humans and monsters. The lower the target's mental resistance, the greater the chance of success. It also has a chance to tame monsters.
- Female Monster Strengthening (女魔物強化): A skill that increases the ability of female monster subordinates.
- Female Slave Strengthening (女奴隷強化): A skill that increases the ability of female slave subordinates.
- Influence:【Pimp】(斡旋：【女衒】): A skill that increases the rewards from the work of female subordinates.
High Tamer (高位従魔師): A high-rank job from the Tamer grouping.
Tamer (従魔師): A low-rank job focused on taming monsters. It has high minion capacity.
- Monster Strengthening (女魔物強化): A skill that increases the ability of monster subordinates.
Harlot (娼妓): A low rank job. It has a passive skill that increased the success rate of Charm.
Enchanter (付与術師): A low-rank caster job focusing on casting buffs. Since Rook's job is not a caster type, normally he cannot use the spells from this job. However, when using Union Jack, he can use spells to buff himself.
Genius: Rook is a genius trained from childhood by his parents to inherit both of their skills. As such, he is a skilled detective, capable of analysing people's thoughts and actions to an uncanny degree and a skilled thief, to the point where he can instruct Elizabeth S. Altar to evade her guards. He is also capable of extremely fast thinking.
Beast Judgement: Rook possesses a natural Beast Judgment skill, which lets him intuit which monster would work best with him.
- Rook chose his name because there was a rook piece on a chessboard nearby when he was creating his avatar.
- Rook's great-great-grandfather, who was also a detective, changed his name to match that of a certain famous fictional detective.
- Due to a traumatic event in his childhood, Rook is deathly afraid of mice.