Barks & natalie.mu wrote that Jaejoong sang some cover songs at last Sun's HALLOWEEN PARTY 2018 and 1 of them was not surprisingly Mika's GLAMOROUS SKY
Jaejoong also covered Remioromen's Konayuki , hide with Spread Beaver Pink Spider & Ozaki Yutaka's Forget-me-not
https://www.barks.jp/news/?id=1000161314
https://natalie.mu/music/news/305924