Aji-no-moto is a brand name for Monosodium Glutamate which is used as a flavor enhancer. Aji-no-moto is made from sugar cane and has been produced in Japan dating back to about 1909.
The product can be purchased in most grocery stores. Some people report negative side affects from foods containing MSG but the product is still widely used in Asian foods and cooking. It can be purchased in bulk bags at Amazon.com: Ajinomoto MSG
If you don't have aji-no-moto you can substitute: