Kyukuro is the son of Elena. He was born after she had been swallowed by the titan. He was saved by Carlo Pikel, an 18 years old scounting legion.
Thirteen years later, he is held captive in prison.
Kyukuro later had an encounter with Charle Innocencio, who had the intention of killing him unknowing that he was more of a prisoner than a threat.
Upon meeting Charle, after he learned her intentions he had placed her knife towards his chest wanting her to kill him. Charle took pity on Kyukuro and spared his life. She had later given him food and brought books which had helped to educate Kyukuro.
Kyukuro had not seen the difference between the titans and humans at first as he believed there was a person outside of the walls. He then saw that humans had feared him as they were afraid of being killed or eaten just as he had insects. After learning this, he decided he was going to meet a titan to prove that he is not a titan child.