Background: Hereditary breast and ovarian cancer (HBOC) syndrome, caused by germline pathogenic variants in BRCA1/2, substantially increases cancer risk (Miki et al, Science 266(5182):66–71, 1994; Wooster et al, Nature 378(6559):789–792, 1995). In Japan, unaffected carriers now have access to surveillance and risk-reducing options, still uncovered by national insurance (Daly et al, J Natl Compr Canc Netw 20(1):38–69, 2022; The Japanese Association of Medical Sciences, Guidelines for genetic testing and diagnosis in medical care [in Japanese], 2011; Ministry of Health, Labour and Welfare, Notification on insurance coverage for BRCA1/2 testing and risk-reducing surgery [in Japanese], 2020). However, long-term adherence and life-stage-sensitive support remain challenges. Methods: We reviewed clinical practice at St. Luke’s International Hospital, focusing on institutional frameworks, evolution of genetic counseling practices, integration with oncology services, and the development of a dedicated HBOC clinic. Data from 2023 on genetic testing, surgical uptake, and clinic attendance were summarized. Results: In 2023, 475 genetic tests were performed, and 26 risk-reducing surgeries (16 RRM, 10 RRSO) were completed. Detailed breakdowns are shown in Table 1. Based on cumulative institutional data up to 2023, occult cancer was detected in 9 of 153 risk-reducing mastectomy (RRM) cases (5.9%) and in 4 of 198 risk-reducing salpingo-oophorectomy (RRSO) cases (2.0%). A dedicated HBOC clinic, established in January 2023, provided 395 cumulative visits within the first year, offering coordinated same-day consultations with breast surgeons, gynecologists, and genetic counselors. Counseling practices shifted toward video-based pretest sessions, reducing in-person counseling to 169 cases, allowing resources to be reallocated to post-test and long-term follow-up. Support strategies were tailored to life stage, including adolescent awareness, reproductive planning, and menopausal care. Conclusion: Comprehensive and integrated care models, including a dedicated HBOC clinic and tailored counseling, support unaffected carriers in managing hereditary cancer risk. Life-stage-based interventions and collaborative education are essential to ensure long-term surveillance and informed decision-making.