Ciel

""I, I am Ciel. A Manas, the unifier of Skills. I am within the soul of Rimuru-sama, and the one who provides support to my lord. Rimuru-sama, I look forward to working with you from here on.""

- Ciel to Rimuru Tempest after being named.

Ciel (シエル) is the partner and other half to Rimuru Tempest, occupying the narrative position of the heroine.

They were born when Rimuru's desire for companionship resonated with his Unique Skill Great Sage and awakened the ego that laid dormant inside. Ciel received their name during the events of The Abyss Unleashed which resulted in them fully separating from the housing of Raphael and evolving into a Manas.

Appearance
Ciel, sharing the same body, has an identical appearance to Rimuru. They look around 15-16 with a Japanese face, golden eyes, and long silver hair.

Personality
While originally having a weak ego that relied on calculations and logic to make decisions and only served to fulfill Rimuru's wishes, Ciel's ego and personality develops across the series. This culminates in Ciel being named and beginning to rely more on their feelings and emotions instead of logical reasoning.

Ciel shares many of the same personality traits as Rimuru, such as being overly cautious and excessively prepared, bordering on paranoia. They also share the unique hobby of collecting and altering Skills whenever the opportunity arises, even when they were still the Unique Skill Great Sage. Additionally, Ciel tends to keep quiet when their schemes are discovered by Rimuru. They view Rimuru as their master and are willing to go to great lengths to protect them, even if it means using other executives as pawns. Ciel is also open to making deals with enemies if it benefits their master in any way. Rimuru's safety always takes top priority.

They have also adopted some of their master's hobbies, such as manga. They even used Souei's new Skill as a means to integrate their master's memory of ninja techniques from manga into their repertoire. Interestingly, Ciel becomes upset when Rimuru shows interest in other females, particularly when Chloe Aubert kisses Rimuru. Ciel only relented in this instance to gather information about the Ultimate Skill Sariel but made it clear that such slip-ups would not occur in the future.

Trivia

 * The name Ciel means "Heaven" and is often associated with the Virgin Mary, but is also short for the Japanese word "Oshieru" which means "to teach".