It was announced at the Jump Festa event that To LOVE-Ru Darkness
will receive two new OVAs to celebrate the franchise's tenth anniversary. They will be bundled with the series' 16th and 17th volumes, to be released on July 4, 2016 and December 2, 2016, respectively. The contents for the 16th volume will adapt chapters 49 and 50 and will be about Sephie, the mother of the three sisters, while the 17th volume will feature manga contents from all the To LOVE-Ru
franchise chosen through voting.
Source: Official site