“To Heart Heartful Party–first official guide book” coming out on August the 12th for 1,575 yen. Has 128 pages. Buy: [Amazon.co.jp] <— no need to use proxy, they ship internationally. It’s main point is the artwork that were only available for the game, but now printed on paper (good for scanners). Also comes with 3 item codes.
To Heart Heartful Party is a social game for mobile phones apparently. Available on Android, iPhone and galake. And it looks like there is no App? You just enter a URL:
[this one http://mbga.jp/_game_intro?game_id=12012772] and then it should work (but needs a yahoo account). You can also play on browser on PC.