Original sentence: Before then Doraemon had been serialized on 6 magazines of Shogakukan, each magazine is targeted to students of 6 elementary school grades.Of course, this helped CoroCoro'''s sales as well.Pokémon's big success in Japan owes to this in a way; the Game Boy game Pocket Monsters: Blue was sold exclusively through the magazine at first.The magazine is A5-sized, about 6 cm (2¼ in) thick, and often more than 800 pages in length, so it is pretty korokoro itself
Edited sentence: Before then Doraemon had been serialized in 6 Shogakukan magazines targeted to students of 6 elementary school grades.Pokémon's big success in Japan owes to this in a way; the Game Boy game Pocket Monsters: Blue was sold exclusively through the magazine at first, which helped CoroCoro'''s sales as well.The magazine is A5-sized, about 6 cm (2¼ in) thick, and often more than 800 pages in length