The grandson and heir to the legendary Tsunehisa (1458-1541, perhaps one of the greater warlords of the early 16th century), Akihisa, who would later be known as Haruhisa, had quite a pair of shoes to fill. His early campaigns were not so terribly auspicious. In 1540, Akihisa led some 20,000 men into Aki with the intent of reducing Môri Motonari's Koriyama Castle. Motonari avoided an open battle and withdrew with Koriyama's walls, resisting an initial Amako attempt to storm the place. Akihisa then contented himself with burning Yoshida - Koriyama's town - and settling down for a siege. Motonari harassed the Amako with a number of sallies, and in October Ôuchi general Sue Takafusa (Harukata) arrived with a relief force. Akihisa was forced to retreat and his noted general Uyama Hisakane was killed defending the rearguard. In 1542 the Ôuchi themselves invaded Izumo but were unable to take Gassan-Toda, retreating in disarray.
According to legend, this defeat was helped by schemes engineered by Tsunehisa, who died soon after wards. Sometime later (1545), for reasons lost to history, Akihisa further weakened his family's once powerful position by ordering the death of his uncle, Kunihisa, the leader of a renowned contingent known as the Shingu army. Nonetheless, the overthrow of [[Ouchi Yoshitaka|Ôuchi Yoshitaka by Sue Harukata in 1551 gave Akihisa a window of opportunity in which to reclaim much lost ground, including a campaign that saw many castles in Mimasaka and Harima taken. Yet by the time Akihisa died, the Amako were hard pressed by the now-formidable Môri clan, who finally took Gassan-Toda in early 1566. Akihisa's successor, Yoshihisa (1536-1610), surrendered and was spared, retiring to Aki to assume the life of a monk.
In an interesting postscript, an Amako family member, Katsuhisa, approached Oda Nobunaga some ten years later and requested that their former lands be restored to them. When Nobunaga went to war with the Môri, he grudgingly accepted help from Katsuhisa and the legendary Amako retainer, Yamanaka Shikanosuke (1544-1578). Unfortunatly, the Môri bottled the two up at Kozuki Castle in Harima province and here the Amako clan played its final act. Katsuhisa committed suicide and Yamanaka was captured, to be murdered soon afterwards.
At their height, the Amako was one of the most highly reputed clans of western Japan. Supported by the Kamai, Uyama, Sase, Ushio, and the Moriyama (among others), the Amako clan could field an army of over 20,000 men. By 1560, the Amako had been weakened by defections and poor leadership, and could call on perhaps less then 10,000.