Real Life: A Homosexual Japanese male who is buff or very Muscular, isn't feminine, and is Sexually active. A man of this class is considered to be a Top, but can often be Versatile.
Manga: Mentaiko, or Bara being the actual term, is Homosexual Manga art that features masculine men with varying degrees of muscle, body fat, and body hair, akin to beefcakes, or bears in gay culture that is mostly pornographic.
Juan: "Hey Daisuke, I'm a Twink. What are you?"
Daisuke: "I'm Mentaiko."
Juan: "What's Mentaiko mean?"
Daisuke: "I'm muscular, I don't act super girly, and I'm a top."