From Yen Press:

With never-before-seen monsters and encounters with some of your favorite characters from the game, the manga adds a whole new dimension to Monster Galaxy!

In a land populated by creatures called Moga, those with the skill practice taming these Moga, capturing them in Starseeds and pitting them against each other in battle. Thirteen-year-old Avery would love nothing more than to become a Moga tamer, but he's needed at home, and there's no way his overprotective mom will let him pursue a dangerous career with the Moga Rangers! Avery and his little sister Dawn have kept their Moga taming aspirations a secret, but the alignment of the thirteen Zodiac planets has sent hundreds of Moga raining down from the heavens, and it's going to be tough for Avery and Dawn to keep their secret when the allure of brand-new Moga is all around!