Try Piano Forge (link below).
There is no piano sheets for His World
You can find it in the related link below.
It depends on the type of virtual piano you're talking about.
You can find piano sheets for the song "Under" by Alex Hepburn on the Music Notes website. The first page of notes is available for free but there is a small charge for the remaining sheets.
Try the link below.
In sheets store
Not really sure what you mean, but pocoapocosheets.weebly.com has a lot of sheets you can check out.
Try the 8notes website or doing an online search for free piano sheet music
One can find easy piano sheet music online in online downloading websites for piano sheets. In addition, some pianists have blogs for piano tutorials and easy piano sheet music.
Well, you can find unofficial piano transcriptions for a few of the songs on Ichigo's Sheet Music (www.ichigos.com). The site includes piano sheets for Still Doll and Vampire Ball.
You can find it for free at - http://www.piano-sheets.net