Sorry to rip an idea, but there's a particular song I've been looking for for quite some time.
The problem is describing it.
For one thing, it's in Japanese.
For another, it is also incredibly gothic. Or perhaps just melancholy. But I prefer gothic.
The guy singing had a pretty deep voice.
The song wasn't necessarily intense or angry, but more so a sorrowful, almost weepy tone to it. Maybe a touch of angst, especially during the chorus which WOULD get intense - but mostly the song was kinda deep.
It also wasn't piano. It was definitely some form of rock or metal.
And I realize that this isn't a lot to go on... :< I would help more if I could, but I cannot speak Japanese, nor do I remember the exact Japanese used.