Koyama Keiichiro (NEWS), Sakurai Sho (Arashi) and Kamenashi Kazuya (KAT-TUN).
There wasn't much further information announced, other than this year's theme - "Confession" (Kokuhaku), and that the show will be held on 26-27 Aug 2017.
This year's the 40th edition of 24hr TV, and there were guesses of the main personality being Arashi, or even a KAT-TUN come back, seeing how the announcement was arranged within the episode of "Arashi ni Shiyare" which had Kame guesting, but it turned out to be the 3 casters at NTV! So many possibilites of how this year's 24hr TV can turn out to be, it's so extremely exciting.
Will update more information as they come!
(Goes back to throwing imaginary confetti in the air)