Approximately one-third of all printed materials in Japan are manga (comics), be they tankobon (books of collected, sequential installments of a particular series) or thick-as-phonebooks weekly magazines which these installments originally appeared in. For the Japanese culture, manga is an institution with as much importance as music or cinema, and with its own unique symbolism and techniques, which often seem nonsensical and confusing to the medium's newcomers. One of the most common of these devices employed in manga is the use of symbols appearing in the region of characters' faces as a humourous way of inflating emotional reaction.
Throbbing veinsAppearance: three or four angled lines resembling arrows without stems all gathered around a central point.
Emotion: anger, impatience, seething
Originally, these were drawn to represent exaggerated veins pulsing in a character's forehead as a comedic means of conveying rage. Like most of the other devices mentioned in this piece, what began as an addition to a facial expression would gradually devolve into a shorthand symbol for a reaction, sometimes now even as a substitute.
The sweatdropAppearance: a single, large drop of water hanging in the air over (or next to) a character's head.
Emotion: unease, indecision, mild frustration
Starting as a normal sweatdrop or two on a character's face, this symbol came to its current state through perspective and distance. If a character was drawn further away, the size of drops had to remain static in order to still be drawn, and seen, in a proper fashion. Like the 'veins symbol', exaggeration of the notation itself came into play, and the single sweatdrop became larger over time, particularly in anime (animation), where it is colored a pale blue.
Blush linesAppearance: a series of slanted lines drawn across a character's face
Emotion: embarrassment, exhaustion, love
This appears in black-and-white manga to indicate humiliation by 'reddening', as it were, a face in a quick and efficient way, without the use of screentones. When carried over to anime, the lines always appear as red, often overlapping the more familiar blushing cheeks.
"Blue" linesAppearance: an array of evenly-spaced vertical lines on a forehead or under one eye
Emotion: shame, disappointment, speechlessness
This type of hatching is similar to the blushing lines above, but is used to indicate a 'blue aura'
and feelings of depression or helplessness. Sometimes straight and sometimes wavy, these lines are always a shade of blue in anime. The background may also become dark and feature a pattern of vertical lines.
The alertAppearance: a handful of short lines all 'pointing' to an unmarked point on a character's face
Emotion: various
These lines or bars have different meanings in different contexts. Often used to symbolize alertness when a character has noticed something important, they can also be seen as 'radiating' joy or rage. In the case of joy, the lines can be wavy. For rage, they might be jagged. The lines may flash quickly for alertness or rage in anime.
Rivers of tearsAppearance: lines representing the outline of thick streams running down the face from the eyes
Emotion: despair, sadness
Different from the rest in that they began in anime and eventually made the transition to manga, these notations are a comedic take on crying. Because they didn't originate in manga, it can be difficult to distinguish these as streams of water, and to a casual observer they may just look like four out-of-place lines scarring a character's visage. The lines can be drawn either wavy or straight. In anime, the streams tend to be pale blue without any outline.
"You should add manga notation to the flower vases and telephones in your home. It might get some laughs and save your family from falling apart."-Koji Aihara & Kentaro Takekuma, "Even A Monkey Can Draw Manga"
