4-koma manga - roughly meaning "four-panel," somewhat similar to American-style comic strips - are very popular in Japan. Some have been brought to the United States, the most popular (and one of the best) being Azumanga Daioh.
Created by the same genius of adorability that brought us Yotsuba&!, Azumanga Daioh follows a class of high school girls going through the daily adventures high school girls go through. Studying for tests, competing in gym class, and gossiping about teachers are rendered with a style of domestic surreality not too far removed from TV sitcoms like The Office and Modern Family.
The cast is full of characters to identify with (or at least laugh fondly at,) from the ditzy Osaka to the kid genius Chiyo to the intimidating-but-actually-shy Sakaki. And Kiyohiko Azuma's art is drawn in a clean and precise style, ensuring that the quietly clever puns and slapstick take center stage.
Azumanga Daioh is especially good for people new to reading Japanese comics - the basic 4-koma format (and the handful of chapters drawn in full-page style) are a great warm-up for right-to-left reading.