|滝島 翠||Takishima Sui|
|Relatives|| Satoru Takishima (father)|
Midori Takishima (mother)
Kei Takishima (brother)
Kaname Takishima (grandfather)
|Seiyū||Kiyoshi H(presentacion en cap 4 )|
Sui Takashima is Kei's younger brother and resembles a younger version of Kei. Initially, he dislikes Kei because he finds living with him disgusting and thinks of him as a "robot wearing human skin". However, he approaches his brother more and to the point where he calls him a lovely brother later in the episodes. Sui likes to call Hikari "Stupid Girl", but approaches her frequently when he thinks that Kei needs help. He is in grade 6, class B at Hakusen Academy elementary school division.
Sui has brown hair and eyes. It is said that both Sui and Kei inherited their looks from their mother, Midori. In the manga, he has blonde hair with green eyes.
Sui is initially introduced as being a very difficult and rude child, especially towards his tutors. Sui used to feel very inferior to his brother Kei, who is good at everything, and believed that he cannot reach his level. He always wanted Kei to care for him as his little brother.
However, when he sees that even his "perfect" brother can become desperate and caring, Sui develops a huge brother complex. He starts referring to himself as a really lucky kid because he has Kei as his elder brother.