[4][5] After graduating from Shim-in Senior High School in Daegu, he attended Seoul National University, where he served as president of the student council in the 1980s.

During this period, he was arrested in connection with the Seoul National University Campus Informant Scandal and subsequently forced to serve 33 months of military service near the demilitarized zone.

Rhyu gained prominence within South Korea's pro-democracy movement after his Grounds For Appeal (항소이유서) was published, challenging Seoul District Court's verdict.

[6] In November 1988, Rhyu married Han Gyeong-hye, a fellow participant in the pro-democracy movement and a Seoul National University graduate in mathematics.

On 25 September 2020, Rhyu sparked controversy in South Korea by referring to Kim Jong-un as an "Enlightenment monarch" after the North Korean leader issued an official apology for the killing of a South Korean official, who had allegedly attempted to defect to North Korea.