[Newprimus]

Even the game's not out yet but I have played the trial version of that, so here's what I can figure from it:

Spoiler:

Main chara is Kazami Yuuji and he's some sort of black-ops operative belonging to a secret division of the Japanese defense ministry. He decides he wants to live a normal life as a normal high school student, so the organization grants him a long leave to realize that desire.

He transfers into a newly established high school for the hyper-elite. Because it's a school that accepts only the best high school students in Japan, there are, including Yuuji, only six students in the whole school, and they're all girls excluding Yuuji. It's also the only school that Yuuji, considering his background and secret occupation, could attend.

Yumiko is the reclusive cool-dere. Amane is the outgoing, mature one who is kind of like the leader of the girls. Makina is a shy but cheerful once you get to know her kind of short girl. Michiru is a daughter from a rich background who's trying to be tsundere, and Sachi is her gentle, proper maid.

Regarding Yuuji, he's badass. Essentially speaking.