Sakuragi Rokurouta, aged eighteen, and referred as 'An-chan' by his cell mates, is the oldest of the seven protagonists in Rainbow. He is strong and has great boxing technique which he used to take on all the six new comers when Mario instigated a fight. Although it seemed he looked down upon the six new cell mates in the beginning, which lead to a fight he won with ease, the six new cell mates found out later that Sakuragi is in reality a guy worthy to look upon and soon start to refer him as An-chan, which can be translated as an 'intimate bro'. The reason why Sakuragi has been detained is unknown. Rumors are he killed his own parents. It seems Sakuragi holds the key to lead the six new comers to the outside world when they end their detention in two years time.
In episode 4, it is revealed that he didn't really kill his father. His father was depressed that he survived a war where his sons died, and Sakuragi said harsh things to him because he didn't understand, causing his father to commit suicide. Sakuragi blames himself, and keeps insisting that he's the reason his father is dead.