Seems I'm getting obsessed with anime songs.
Growing of My Heart - Mai Kuraki (Detective Conan) i said before.
Answer - Flow. From the live-series of Detective School Q (so it's half an anime...) and now...
Brightdown - Tamaki Nami
I downloaded the opening of D.Gray-man last month and loved Brightdown. Then got the PV yesterday.
The past 4-5 releases of her had really depressed me, as I thought they didn't have the fast catchy beat of her early songs (except Heroine, which i liked). The song is perfect, the beat is perfect, and the PV is perfect+1.