When Sean was born, he took the life of his mother as a sacrifice. Sean was an experiment attempt by the hidden village of Sand to ‘build’ stronger ninjas.
Before the Chuunin exams, Sean has never been hurt as the sand always protected him. He has never slept in years either as the Sand demon would take over his body and eat away part of his mind everytime he lose consciousness. Thus, Sean has become quite mentally unstable. He has never felt love as his villagers feared and loathed him. His father, the Kazakage, sent ninjas to assasinate him since he was 6 years old as his powers was getting out of hand. The 1st of the assasins was Sean’s uncle whom he thought was the only person who loved him.
Ever since the incident, Sean ‘tattooed’ the kanji ‘love’ on his forehead and swore to love only himself and sought to feel his existence by killing others. He was sent along with Temari and Kankurou on an A-rank mission. Seemingly to take part in the Chuunin exams in Konoha, Sean transforming into the Shukaku was actually the Sand’s trump card in their plan with the Sound to destroy Konoha. However, he was defeated by Naruto and escaped back to the Sand with Temari and Kankurou.