Timid 16-year-old Kira Asou prefers to be alone drawing than stand out. At a park, she is approached by her schoolmate Rei Kashino—notorious for being a womanizer—who asks for directions. Distrustful of Rei's intentions, Kira quickly chalks a map for him and runs away. Little does she know that Rei finds one of her sketches on the back of the map and becomes captivated by her artistic skills.

Much to Kira's chagrin, Rei immediately recognizes her at school, but she ignores his attempts at striking up a conversation. However, Rei's sincere praise about her drawing leads Kira to see the violent rebel in a better light. After watching him kiss a statue of the god Mars, Kira feels so moved that she instantly requests him to model for her.

As Kira and Rei's chance encounter begins to develop into a flourishing relationship, what is to become of these two polar personalities?

Mars was re-released in eight 2-in-1 omnibus bunkoban volumes, including an additional story, from October 12, 2006, to January 12, 2007.

The original release was published in English by Tokyopop from April 23, 2002, to November 11, 2003. After the company went defunct, Kodansha USA acquired the license and later digitally republished the entire series on June 12, 2019. Both the original and the omnibus versions have been released in French and German by Panini Comics and in Italian by Star Comics. Meanwhile, only the omnibus has been translated in Spanish by Arechi.

The manga was adapted into a Taiwanese television drama, which aired from July 31, 2004, to October 23, 2004. In 2016, it was re-adapted into a Japanese television drama titled Mars: Tada, Kimi wo Aishiteru and a sequel film under the same name.