Japanese prayer for the dead

Hi,
My mother was really into Japanese culture, she died when I was 15 and now I'd like to get a Japanese prayer for the dead, kinda a protect the soul script so I can have it tattooed on my back encircling my mothers picture.

Typically, sutras (Buddist scriptures) are read in Japanese funerals, of course by a monk. Why not visit a temple of a sect that your mother might have prefered. I'm sure they can explain it better than me. Other than the sutras, there is no specific Japanese prayer for the dead. People are free to pray in Christian style, Muslim style or your own style.

As Uco mentioned, there is no specific prayer for the dead. For Buddhists, gratitude and prayers for the deceased are dedicated during mid-summer obon season. Sometimes prayers on slips of paper are put onto miniature wooden boats to float down the river to "the other shore". Obon festivities include bon odori (folk dancing), a dance of joy as a tribute to the deceased. Google "ullabon"(sp?)and Buddhist.

A central belief of Buddhism is impermance, in other words, everything is constantly changing. Since a tattoo is permanent, wouldn't it be the exact opposite of want your mother would want?

You should not pray 'Nam myoho rengekyo' unless you are a Nichiren follower and not 'Nam amidabutu' unles you believe in Nenbutujodo.
These two buddhist sects are both popular but very different, as Catholic and Orthodox churches. If you do not want to commit a particular sect, I recommend Hannya Singyo, which is respected by most Buddhist sects.
色即是空、空即是色