"Pachai Vayal Manadhu" could be a song by S.P. Balasubrahmanyam, a renowned Tamil playback singer. His popular songs include "Pachai Vayal Manadhu" from the movie "Kumki." I should verify that. Yes, the movie "Kumki" (2012) features that song, which is a duet with Latha. The lyrics are by Vairamuthu, so that's a key detail.