Cancer remains to be the leading cause of death in Japan, but recent progress in cancer therapy has improved the long-term outcome for cancer patients. On the other hand, the patients suffering from cardiovascular diseases are increasing explosively in number because of the westernized lifestyles and progressive population aging. Under such circumstances, it is increasingly of importance to manage the cardiovascular complications, which are related to both cancer itself and adverse effects of cancer therapies. To cope with these problems, we have initiated interdisciplinary collaboration between oncology and cardiology specialists in clinical practice, and also launched the Japanese Onco-Cardiology Society in 2017 to integrate the many different perspectives of clinicians, researchers, regulatory scientists, co-medical workers, and even patients. Following the release of the landmark 2022 European Society of Cardiology guidelines on cardio-oncology, JOCS, in collaboration with the Japanese Society of Medical Oncology (JSMO), published onco-cardiology guidelines in March, 2023. Both guidelines provide recommendations for the management of a broad spectrum of cardiovascular complications and diseases in cancer patients, but we should acknowledge the lack of strong evidence for many of the recommendations, and need to deploy a bridgehead toward the next stage of cardio-oncology. Our goal is to promote the cardiovascular health of cancer patients and cancer survivors by elucidating epidemiologic and pathophysiologic aspects of cardiovascular complications and by establishing diagnostic strategies with risk prediction and evidence-based therapeutic strategies against them.