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masturbation
オナニーは多くの人が経験する行為だ。
Masturbation is something many people experience.
性教育ではオナニーについても取り上げた。
Sex education also covered the topic of masturbation.
青年期にオナニーで自分の体に慣れるのは珍しくない。
It is not unusual to explore one's body through masturbation during adolescence.