Background: Adolescents and young adults (AYA) with cancer go through various life events during their illness trajectory, and there is often insufficient information on their diseases due to their rarity. Few chances are available for AYA patients to meet and share information with each other. Therefore, at the National Cancer Center Hospital in Japan we hold AYA Hiroba, a monthly get-together for AYA patients to communicate with each other. This study investigated satisfaction and effect with the activity. Methods: We have held the AYA Hiroba activity once a month since May 2016. We asked participants to complete a questionnaire at each session.Results: We held the activity 33 times between May 2016 and May 2019. A total of 130 patients participated, and 97 of them completed the questionnaire, including providing demographic data, since October 2017. The respondent demographics were as follows: sex (male/female), 38/59; median age, 29 years (range 14–39 years); outpatients/inpatients, 31/66; number of sessions attended (1/≥2), 42/55; and cancer type (sarcoma/malignant lymphoma/brain tumor/germ cell tumor/leukemia/melanoma/breast cancer/neuroblastoma/Wilms tumor/lung cancer/cervical cancer/nasopharyngeal cancer/tongue cancer/blank), 45/11/9/7/6/5/3/3/2/1/1/1/1/2). Many attendees perceived the activity favorably: “It was very satisfying” (61.7%), and “It was very helpful” (65%). The feedback was classified into three categories: “interaction with the same generation”, “diversion”, and “getting information”. Discussion: AYA patients have a great need to communicate with each other, and the feedback suggests that AYA Hiroba would be effective in interaction with the same generation, diversion and getting information. Most participants were very satisfied with the program.