Wada Koremasa era partidario del shogunato Ashikaga, Oda Nobunaga lo apreciaba, ante él llevó en audiencia Wada al padre Luís Fróis. Combatió al clan Kiada y murió en la batalla de Shiraigawara en 1571, donde apoyado por el clan Ibaraki fue derrotado por Araki Murashige y Nakagawa Kiyohide. En la batalla luchó su hijo Wada Korenaga. A pesar de su inferioridad numérica, Koremasa atacó con 200 jinetes en Mazuka. Lo mató Kiyohide. Los Ibaraki atacaron el campamento de Murashige (al que protegían 300 arcabuceros) y fueron derrotados:
After losing their two commanders, the remnants of the Ibaraki and Wada allied army charged out in the spirit of encountering an honorable death in battle and were almost completely annihilated. At this time, the Shiraikawara was said to be white in name only and flowed blood red.
Once the trailing army led by Wada Korenaga received news of the defeat, the forces returned to Takatsuki Castle and, along with Takayama Tomoteru and Takayama Ukon, strengthened the defenses at the castle.
The allied forces of the Ibaraki and Nakagawa attacked and toppled Ibaraki Castle. After attacking Kōriyama Castle, the army proceeded to surround Takatsuki Castle. Matsunaga Hisahide and Matsunaga Hisamichi (father and son), along with Shinohara Nagafusa (a senior retainer of the Miyoshi family of Awa) joined the siege, while the town below Takatsuki Castle was destroyed after burning for two days and nights.
At the time, there were Christian churches in the environs of Takatsuki Castle under the protection of the Wada and Takayama clans. Observing these developments, the Jesuit missionary, Luís Fróis, dispatched Lorenzo Ryōsai (a Japanese convert to the Jesuit faith) to inform Oda Nobunaga of the situation. After learning of these battles, on 9/9, Nobunaga sent Sakuma Nobumori to warn soldiers in Takatsuki Castle to withdraw. Neither army, however, moved so, on 9/24, Akechi Mitsuhide led 1,000 soldiers to engage in mediation. It was at this stage that Murashige decided to withdraw.
Thereafter, Murashige entered Ikeda Castle while Kiyohide entered Ibaraki Castle. The Miyoshi forces passed through Takatsuki and approached the capital. In the twelfth month of 1572, Miyoshi Yasunaga, Shinohara Jiton, and Shinohara Nasashige each issued prohibitions to the Rikyū-Hachiman Shrine in Ōyamazaki in Yamashiro Province. Meanwhile, Wada Korenaga became the lord of Takatsuki Castle, but came into conflict with Takayama Tadateru and Takayama Ukon (father and son). In the third month of 1573, Korenaga was ousted from Takatsuki Castle by the Tadateru and Ukon with the support of Murashige.
Details of the events leading up to the confrontation between the two armies on 8/28 at Shiraigawara remain uncertain. However, while hostilities broke out before the allied forces of the Ibaraki and Wada could organize sufficient resources, the Araki and Nakagawa forces had already prepared ambushes, so it can be surmised that the battle was initiated by the Araki and Nakagawa.
Owing to this battle, the Three Military Governors of Settsu (Ikeda Katsumasa, Itami Chikaoki, and Wada Koremasa) appointed by Nobunaga lost power, while Araki Murashige, Nakagawa Kiyohide, Takayama Tomoteru, and Takayama Ukon came to the forefront as influential bushō in Settsu. In this respect, the battle marked a transition from the Sengoku period to the early Azuchi-Momoyama period.