Necklace of Fate

The Necklace of Fate is a key item held by Satoshi.

Story
The necklace was given to Satoshi by his father, before he died. The necklace unlocks the soul of the one who wears it, and in the event of extreme emotional trauma, may cause the person's soul to split. The trauma Satoshi suffered from the death of his father was more than enough to cause this, forcing his original soul to split into two, and later into four. The necklace can allow Satoshi to access his other souls, though it alters his personality when he does so, and acts as a lock on the others. The lock also prevents his souls from directly influencing his mind, though this may weaken at times, and in the case that the necklace is removed from Satoshi, dissipates completely, leaving him completely at the mercy of his souls. However, only one of his souls is dangerous, though if it is able to take control with the lock weakened or gone, it drives him into an uncontrollable rampage.