Following on from Sony's western-focused E3 showing, and the likelihood of a similar but Vita-heavy slant during Gamescom, the next big opportunity for Japanese developers to show off their Vita wares will be in this month's Game Heaven event (date as yet unknown). The first Game Heaven, was a poorly described release of a bunch of YouTube videos.
According to a Dengeki article with Sony's SCEJ boss, translated by Andriasang, "The next Game Heaven event will be an actual event that you'll want to tune into from start to finish, and not just the sudden release of information like the first Game Heaven. Outside of just new information, Sony will partner up with companies to share development secrets and get deep into the heart of games -- things that users would want."
What do you expect to see? Monster Hunter (if it exists) is likely to be kept back for Tokyo Games Show, but there are lots of other developers working out there, who finished up their launch Vita projects long enough ago to be putting up some second-phase efforts. Looking through the Japanese sites, there's been a sudden drop off in Vita news which suggests somethings are being held back.