1) Collective pseudonym 
The two of them grew up together and went to the same elementary school and have been best friends ever since. Both started as doujinshi manga artists, but not as Peach-Pit. Then they were scouted by Dengeki Comic Gao!. In 2008, one of their manga, Shugo Chara!, was awarded the Kodansha Manga Award for best children`s manga. Shugo Chara was also ....
[n] - the stone seed of a peach
noun the stone seed of a peach