Yes, SHIATSU is a Scrabble word!

Letter values in Scrabble US: S 1, H 4, I 1, A 1, T 1, S 1, U 1.

Is it a valid word?

SHIATSU is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

treatment of symptoms by applying pressure with the fingers to specific pressure points on the body

Also: g-jo.