Kelantan's Sultan Muhammad V, seen here reading the Oath of Installation, was officially installed as the 15th Malaysian king yesterday under the country's unique royal rotation involving the nine Malay ruling houses. The installation ceremony, steeped in royal Malay customs, marked the formal commencement of his tenure as the supreme head of state of the Malaysian federation. Sultan Muhammad V, 47, had taken his oath of office on Dec 13. Under the rotational monarchy system, one of the rulers from Malaysia's nine royal houses takes turn every five years to become the Malaysian king.