Pirania & Piranha

Why is this site spelt ‘pirania’ ?

Pirania is how Japanese pronounce and spell the word piranha.
In Japanese piranha is written like this.    ???? pi = ??ra = ? ni = ??a = ?

To encourage Japanese to come to this site and for it to rank high on Yahoo & Google’s Japanese versions it is better for it to be pronounced ‘Japanese’ for our Japanese customers.