The official Japanese website for Yakuza seems to be teasing an announcement that will take place on May 24. As it's already been confirmed to be in development in months long past (Sega's even been conducting their search for hostess models), we can only assume it's Yakuza 5.
After Sega took a risk in localizing Yakuza 3 and it paid off, they've been quick to bring over all the console titles since. This reveal being so close to E3, one would hope Sega plans to announce Yakuza 5 for the western market there, but given their current financial situation, I wouldn't bank on anything. They may need to play it safe now more than ever before.
via Gematsu