Lantis Matsuri attendees should stop by the Highway Star special booth in the lobby area on the second day and show their Ro-gumi membership card to get a special sticker. Plus members of the mobile fan club can get a special wallpaper. For more details, see the official website.
To commemorate Lantis’ 20th year, the main Gamers store, in Akihabara, will have a special corner featuring Lantis artists. And from May 8~26th, if you buy a Granrodeo CD/DVD/Blu-ray at the store, you will receive a special campaign bromide (see above).
For more details, see the Lantis announcement.