This chapter investigates the usage of Japanese emoticons (kaomoji, 顔文字) in posts and comments of 1,125 Japanese Facebook users, with a focus on generation and gender differences. The analysis of 2,454 kaomoji revealed that they were more frequently used in comments than in posts and more often added to shorter sentences than to longer ones. Women under the age of 30 had the highest proportion of kaomoji use, while men over the age of 60 the lowest. Japanese men over the age of 60 used a more diverse range of kaomoji than women (highest type-token ratio). In contrast to Western emoticons, kaomoji examined in this study did not function as markers of irony, unless combined with different notations of laughter: 笑, わら, or w. This usage was only found in the data of users under the age of 30, irrespective of gender.