You got me and I got you

Kang Jenny and Lee So Yeon used to be best friends when they were kids but now that they are grown ups and in their own world they can't tolerate each other. Each of two are very big names in entertainment industry. One is 12 Grammy winning Singer and other is 2 times Oscar winning Actress and both belong to the same company. One day the two realised that they were fighting over something in the past and regretted each thing they did in the past and asked for each other forgiveness. They came on good terms and became friends again but then while saving a kid they both end up dying. To their surprise they wake up to when they were 17 (16 international age), the age when their feud began. Regretting everything, they swear never to fight again and live their lives to fullest, but that is not possible as someone is there to set their friendship on fire.