This style was called Japanese penhold. Although it is common not only in Japan but in Korea, Taiwan, and in many other Asian countries.
The main distinction from a Chinese style is the shape of the table tennis paddle and handle and the placement of the fingers behind the blade. The thumb and the index come together upright more closely, but mainly, the middle, ring and little fingers lay straight against the back of the blade.
This provides an advantage in power since those fingers are behind the contact point on the blade and add to the force of the stroke. Probably the biggest shots in table tennis have been produced with this grip. The disadvantage is restricted flexibility.
The backhand is even more hampered than that of the Chinese penholders, so it places even greater demands on footwork.