Question: A singer who is a quarter Japanese, a quarter Chinese, and half German, is a member of a Japanese boy band that is managed by Johnny & Associates, and had an average age of what when they debuted?
Sentence (from "Kanjani Eight"): Kanjani Eight (関ジャニ∞（エイト） , Kanjani Eito , stylized as Kanjani∞) is a seven-member Japanese boy band from Japan's Kansai region.
Relevant evidence: No