Based on the erotic game by Clock Up.

Will there be a season 3 of the Sekirei anime series?

It has been seven years since the second season of Sekirei aired, but the possibility that the show will continue still tantalizes fans.
Season two ended with “to be continued,” and there are a few fan-created petitions circulating online that call for the show’s creators to continue the series. Many fans speculate that the anime series caught up to the manga too fast.
Now that the manga series concluded in 2015, and the sequel manga began this year, perhaps the show runners will pick up the Sekirei anime again where they left off. Although the anime’s director Keizō Kusakawa has said in interviews that he would like to continue working on the series, at present there are no public plans for a Sekirei season 3 release. Sources: Sekirei Season 3: Will it happen or not? Updates for 2018 Release Sekirei - Wikipedia