The 67-year old won Friday’s vote after it was pushed into a runoff with Sanae Takaichi, the economic security minister, blocking her path to making history as the country’s first ever female prime minister.
Mr Ishiba takes the helm of the world’s fourth-largest economy at a time of geopolitical volatility in the Indo-Pacific region and increasingly troubled ties between Tokyo and Beijing over China’s territorial ambitions, particularly around the disputed Senkaku Islands.
Earlier this week, China test fired an intercontinental ballistic missile into the Pacific, reportedly without giving Japan prior notice. Japan also faces security threats from nuclear-armed North Korea.
The new Japanese leader has previously proposed a Nato-style collective security to counter these threats and he supports Taiwanese democracy, having declared that: “If there is an emergency in Taiwan, it is an emergency in Japan.”
He is an advocate of a strong Japanese military that should be able to take a stronger response if its territorial airspace or waters are breached. But he also chooses his words carefully when it comes to China and has called for deeper engagement and more diplomacy with Beijing.
The former banker first entered politics in 1986 and has served as defence minister, agriculture minister and secretary general of the LDP. His latest bid for the leadership was his fifth attempt and self-described “last battle” to reach the top.
“We must believe in the people and speak the truth with courage and sincerity,” Mr Ishiba said after his victory was declared, reported the Asahi Shimbun newspaper. “I will do my utmost to make Japan a safe and secure country where everyone can live with a smile on their face once again.”