Ishiba has consistently pushed for stable ties with China and, observers said, any further advances could be on hold with a new leader.
“If somebody like [Sanae] Takaichi, who is well known for her tough stance against China, becomes the next leader, the relationship would certainly cool down, said Toru Horiuchi, a lecturer in Sino-japanese relations at Chinese University of Hong Kong's school of governance and policy science.
Takaichi is considered one of the most hawkish politicians on China within the LDp, She is part of an ultra-nationalist group with a revisionist view of history and has visited the Yasukuni Shrine a number of times.
The shrine in 'Tokyo commemorates 2.5 million japanese war dead, including 14 Class A war criminals from the second world war, Visits to the shrine by politicians anger Chinese, because of japan's 1931 invasion and occupation of China and the atrocities its troops committed there.
Zhang Yun, a professor of international relations at Nanjing University, said fapanese politics was becomingfragmented, with the opposition parties unable to unite and no consensus within the LDP to remove Ishiba.
“Ishiba is likely to face a multitude of diverse and often conflicting voices within his party and among the opposition parties, making Sino-japanese relations unpredictable. This uncertainty stems from the internal fragmentation and the difficulties of navigating such a complicated political landscape,” Zhang said.
The ruling LDP is broadly seen as a right-leaning establishment party, but its approach to China has varied over the decades as prime ministers have come and gone.
Ishiba has been more pragmatic on China ties than his predecessor, Fumio Kishida, helping to improve relations by holding several high-level dialogues between the two countries.
Ryo Sahashi, an associate professor of international politics at the University of Tokyo, said a more right-wing leader would sharpen the security focus on Beijing.
From their perspective, economic decoupling from China is considered a security imperative They're likely to adopt extremely hardline positions on historical and territorial issues as well,” Sahashi said.
Wang Guangtao, an associate professor at the Centre for Japanese Studies at Fudan University, said that even if Ishiba stayed, ties were unlikely to improve dramatically - although there would be more predictability.
“At present, Ishiba's low domestic approval ratings offer little help for advancing Sino-japanese relations. Should his support remain persistently weak, he may ultimately have to resign, he added.
Various polls put Ishiba's approval rating in the low 20s, the lowest level since he took office in October.
Wang said Beijing would undoubtedly welcome a Japanese leader in favour of stable development.
But both China and neighbouring countries should brace for potential headwinds if a more conservative or right-wing politician assumes power, especially given the sensitive timing of this year - the 80th anniversary of the end of World War Il,” he said.
Sahashi said dramatic changes in relations were unlikely if other contenders - cabinet members Shinjiro Koizumi, Yoshimasa Havashi, and Katsunobu Kato- became prime minister.
“They appear more inclined to balance japanese economic interests with security concerns, and would likely seek subtle readjustments to Japan's position within the international order currently being destabilised by the Trump administration, he added.
just as the Trump administration negotiates with China, there's a rational case for Japan to value Japan-China relations - a point that tends to be overlooked when more right-wing, conservative leadership emerges.