A facial expression where the character appears to be in an ecstatic, yet quiet and unresponsive trance with their face almost melting in pleasure.
The cheeks look flushed, the eyebrows are slanted downwards towards the sides, and the eyes are half-open and moist, often staring into the distance.
It is common to see drool and a half-open mouth as well. The limbs and joints may be relaxed and hanging loosely in place.
Example: post #1164935
It is often sexual in nature, but not always. It may also be seen when a character is eating their favorite food, for example.
Not to be confused with ahegao, which is a more wild expression. Torogao indicates trance-like pleasure.