It looks like UNB and Uni.T may be having a project together.
UNB released a teaser featuring two of the UNB members and two of the Uni.T members with the caption "We are together". The teaser image also has the numbers 9 and 18, which probably alludes to the fact that each group has 9 members for a total of 18. UNB has also previously released a teaser for "BLACKHEART".
Whether it's a UNB comeback or a dual project, "BLLACKHEART" will be released on June 28th, so check out the teaser below and stay tuned.