@SuperDicq >struck a deal with copyright holders of both the Tetoris song and the character?
I believe the tune is so old is has fallen out of copyright.

I'm not sure if the copyright holder of the original character is known.

>Suiseiseki is a proprietary character.
Ah yes, I need to ask the copyright holders to relicense to a free license (it appears that in this rare case the artists remained the copyright holders rather that some business).