'The World' is the most advanced online game ever - a game full of fantasy and adventure! When fourteen-year-old Rena wins a contest that allows her to use the avatars of the legendary dot hackers known as 'Kite' and 'Black Rose', she convinces her game-hating twin brother Shugo to give it a chance. But things quickly go wrong, as the beginner players are attacked by a monster far beyond their level. Shugo is killed by it, but is revived by a strange girl called Aura. She also gives Shugo a weird bracelet, telling him that he must carry on the legend of the dot hackers; then she disappears. Together with Rena, and many new friends that he meets while in The World, Shugo embarks on an adventure to discover the secrets of this mysterious bracelet.
Both of these are short adventure/action manga about a group of kids inside a digital world (hack's world being inside a game). They both have tons of "friendship"-type scenes, feelings for digital beings, and a few action scenes. If you enjoyed one, I recommend you check out the other.
Both of these manga are action shounen for younger readers. They both deal with kids fighting with monsters and the corny "friendship is power" themes. When reading Digimon Next I was reminded of GX more than the other Yu-Gi-Oh series. If you're a fan of one, I'd recommend the other as well.