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Kiel was first introduced in chapter 131 of the web novel as a slave owned by the Slave Merchant in Melromarc's Castle Town. He is described as a young man around the age of 10 with dog-like features. When Naofumi tells Raphtalia to choose anyone he recognizes from her village and Kiel is the first. At first he doesn't recognize her because of her grown up appearance, but when she recounts the time he was looking for a pretty shell to give "Father" for his birthday so he dived into the ocean and almost drowned but was saved by Sadina as well as the time he accidentally ate a poison mushroom he found in the field, messed up her stomach, and hid to avoid being scolded so when she, Raphtalia, found him she was told to keep it a secret including that he had even wet his pants. After all was said he immediately acknowledged who she was. After having an unconvincing conversation with Raphtalia, Kiel agrees to become Naofumi's slave with the hope of returning to the village.
Although she identifies as male, in chapter 137 it is revealed that he is actually a she. She rebuts with "father said that a man is a man if he thinks he is a man no matter what" but the revelation still throws her into moderate confusion. Kiel wasn’t meant to be an important character, however the personality she was given overlapped with another male character that was already firmly planned to be made down the road, so the author decided to give ‘him’ a little "quirk". She is presumed to be the "Guardian of Divine (crepe) Tree" in the Christmas Special.
Kiel can be bratty and whining, when wanting food from Naofumi. Despite how she acts, she helps bring together the slaves, and acts as a sort of leader. I thought she was growing to be a gluttonous battle maniac, but she was able to cook as well, showing a girly aspect. Kiel has been shown to be a charismatic person by nature. Her actions are shown to be too erratic.
She is initially described as a young man around the age of 10 with dog-like features, however as she levels and her appearance ages as well as her being verified to be female she is made out to be more of a tomboy who could easily pass as a pretty boy.
She looks exactly like a puppy. As for breed, she looks like a Siberian Husky. She is a loincloth-clad puppy walking on two legs.
This form is of a dog with three heads. That of Cerberus, the guardian of hell. Her form isn't particularly large. Since the base is Kiel, it still looks like a wolf cub-like Cerberus. Looking from afar, her outer appearance is still relatively cute. She turned into what she feared to obtain strength, the Cerberus demon that destroyed her village during the wave. She thought something like strength = evoking fear. She’s really fast. Her weaknesses are being unable to look away from sweets, and being weak to lullabies.
Throughout her life Kiel was raised as a boy, her father treated Keil like his son, and told her that gender was a state of mind.
Two months before the first wave, Kiel was looking for a pretty shell to give Rafatalia's father for his birthday so she dived into the ocean. She almost drowned, so Sadina jumped in to rescue her.
She also, accidentally ate a poison mushroom she found in the field, it messed up her stomach, and she hid to avoid being scolded. She told Raphatalia to keep it a secret when she found her. She even wet her pants.
- Kiel wasn't meant to be an important character, however the personality the author gave him overlapped with another male character he planned to make down the road, so he decided to give ‘him’ a little… quirk. (Sex change)