Se7en's label ELEVEN9 recently provided additional details regarding this comeback, stating, "Se7en will release a new single album titled 'Rainbow' on July 7 and officially kickoff his promotions in Japan." If what Eleven9 Entertainment says is true, then 'Rainbow' will mark Se7en's tenth single album. His last single album, 'Arigatoo,' was released back in 2013.
I guess we will have to wait a bit longer for Se7en to make an official comeback in Korea. We can only hope that it's coming soon!