Mon Colle Kids

Mon Colle Kids is a five volume manga that ties in to the anime …. sort of. It's like an apology for the anime, where subtly bashes (read : it's opening scene already features the hero being scolded for having a stupid card obsession) card game obsession and where you'll see the heroes doing all sorts of free time activity except playing card games.

So, now there's a manga all about playing card games and taking them serious and stuff. There's the impulsive hero, the rival, the mentor, and for a small twist, the tactics geek who is also the love interest and Utahime. One other thing of note is that Hitoshi Yasuda appears as a character, and the creator of the game; he is the reason there happens to be a card game in the human world that coincides with Rokumon Sekai.