User blog comment:B214/Question & Answers 5/@comment-26473512-20150608133504/@comment-16281343-20150608135352

http://jisho.org/search/%E5%85%85%20%23kanji

Kyuu basically means fulfilled. A riajuu is a person that is living a fulfilled life.

On the context of being used by high schoolers, it usually means that person is popular.