Somewhere in my heart I do believe I had a chance (to find you)

AAAAAAKH

I have this song stuck in my head for days since watching Jishaku Otoko 2015. Even if I try writing the lyric, google doesn't show any clue. I have no idea who sing this because I've been away from american music for years. haha

It's weird because I think I'm pretty good at finding japanese songs. Remember that choir dorama, Omotesando Koukou Gashoubu? Yup, I list the whole song they sung here. But, I'm so clueless about this song. It sounds like a broken heart song (of course) and I'm so much in love with the voice. 

How about you? Recognise that song?