I usually don't bring it up myself, since I have plenty of other interests...heck, I'm more of an otaku about Medieval/renaissance warfare, history, language and sports stuff. I will however explain, that I listen to jap music and like some jap art, go to the summer festival our jap embassy organises and sometimes make jap sweets and dishes. That's enough of a show of power level in my mind, any further and sensors will malfunction.
If somebody mentions manga, anime, lns, I am completely open about it.