How do you spell Ryan in Japanese?

呂 (ryo) generally means 'bass range' in Japanese music, as in contrast to 甲 (kan) which means 'treble range'. It could also refer to a specific scale of an old sort of Japanese formal music called gagaku, in which sense it also might appear as 呂旋 (ryo sen) or 呂旋法 (ryo sen pou).