ComiXology has added all 15 volumes of Fuyumi Soryo’s Mars manga and all 14 volumes of Yayoi Ogawa’s You’re a Pet (Tramps Like Us/Kimi wa Pet) manga as comiXology Originals. Kodansha Comics is publishing both series.
Soryo published Mars in Bessatsu Friend from 1996-2000. Soryo also wrote a one volume Mars Gaiden prequel manga. Tokyopop published all 15 volumes of the manga and the Mars Gaiden prequel in 2002-2004.
Tokyopop published You’re a Pet under the title Tramps Like Us in North America.