[7] On the variety show "Miss Back", Ryu revealed she had been diagnosed with depression and panic disorder, sharing that her medication caused her to suffer from memory problems.

[11] On August 1, 2015, Ryu released her first solo indie EP album "SeRen:Ade".

[15] On March 2, Ryu released a single album "Stay Real", managed and published by her new agency.

[16] Later that month, Ryu held a second solo concert titled "Spring Rain" at Olympic Hall Muse Live stage,[17] followed by a concert titled "Sun Shower" held on June 23, 2018, at CKL stage.

[21] She appeared as a contestant on the music survival reality show Miss Back between October 8, 2020, and January 26, 2021, where she became a finalist.