PCP: Kotou no Kodomotachi

Perfect Crime Party is about three elementary school children who decide to form a Perfect Crime Club, performing seamless acts of crime. At the beginning of the series, their crimes are as simple as putting a dirty tray on the desk of a boy that already took returned his tray without being caught, or switching seemingly identical items. The plot follows the group's efforts to commit perfect crimes within their school.

(Source: Bakuman Wikia)