Jayin was an Alaafin of Oyo and the son of Oba Kanran. He was considered to be an effeminate and dissolute prince prior to his accession to the throne. As king of Oyo, his Harem was usually filled with varied sort of characters. However, it was his son who carried the hopes and aspirations of the people during his reign, in the process triggering jealousy from the King.
Prince Olusi, Ajayin's son, was kind and generous, but his stay in the palace was short-lived. He was raised in his father's house and one day succumbed to a tryst with one of his father's wives. The prince was caught and inevitably had an audience with Jayin. In the meeting Jayin could not control his jealousy and betrayed his emotions by poisoning the prince leading to Olusi's death.
Olusi's death was a tragic event in Oyo and shattered the hopes of many citizens, the chiefs then began to suspect foul play and vowed to find the cause of death. During Olusi's funeral, the King was asked to abdicate the throne, preferably committing suicide.
It was during Jayin's reign the title of Awujale of Ijebu was created.