Kaidou Toki

Toki Kaidou (海藤 時, かいどう とき lit. Kaidou Toki) is Shun's little brother who looks up to him because of his great accomplishments like being a gang leader and a savior. These were all actually exaggerations Shun made after boasting about himself.

Personality
Toki is fond of Shun and looks down to others like Kusuo and Riki whom he thought his brother's underlings. He was revealed to be stronger than Shun as he was able to flip a high school student delinquent.

Appearance
Toki bears striking resemblance to Shun's pre-chuunibyou appearance with his hair down. It is implied that he was copying Shun's style of clothing like wearing long sleeves when Shun wears long sleeves or collared shirt.

Trivia

 * Toki 時 means time, and Sora　空 means sky (or empty), but when 空 is combined with the character 間 it becomes kuukan 空間 meaning “space” (like physical space, not outer　space)- so when you put their names together (with the kaidou -> kan idou) you get Jikuukan Idou (時空間移動) = travel through time-space (ie another way to say time travel)