Mirai Nikki may be receiving a second season as the final episode ends with a mention of a “next project” – explicitly confirming that there will be more to the series, likely meaning an anime following Akise Aru.
Currently, Mirai Nikki spans 26 total episodes and the series surrounds a premise of a survival game – and while the final episode is more or less conclusive, it appears there’s still much more the series wants to show us. Of all the available methods Mirai Nikki could go about this, the most reasonable possibility is that this proposed “next project” could be an animation of “Future Diary: Paradox”, a branch of the manga separate from the main story which follows Akise Aru and Murmur in an alternative timeline.
That belief further seems the most plausible when one considers that Mirai Nikki says to look forward to its “next project”, indicating a different work of the same series – rather than saying “to be continued”, which would have meant more of the same. In any case, we now await the “next project” eagerly.