Jaakuna Kokoro(邪悪な心 literally meaning evil heart) is Yasashī's cousin.
Jaakuna grew up with no parents and was loney for most of his life. He despised all his cousins because he thought they didn't know what it's like to be alone, and they were never alone because they had each other.
Jaakuna used to be very kind to his siblings and cousins. When his father died, he started to distance himself from them. He enrolled in the Academy and trained everyday after school since he didn't really have anything else to do. One day when he was training, he heard a voice and that's what made him go Rouge once he became Chūnin.
Jaakuna killed his siblings and escaped the village making him a Rouge Ninja. Although, only one sibling survived because that sibling was in Konoha at the time. Jaakuna later moved to Otagakure but escaped after almost getting killed by Karin and he asks her if her name is Karin. He then tells her that he is from Kusagakure and then he disappears.
When he was a child, he wore a baige shirt with the Hidden Grass symbol on it. His orange pants went down to his knees and for shoes he wore blue calf length sandals.
In part one he wore a