This is what we know about the game so far :
This game sole male is a shota, a cute pint-sized guy who looks like a small girl, and there is no alternative protagonist. If you're into tall and manly heroes, you're out of luck.
It will feature cross-dressing. Expect this little dude to be sometime dressed as a female and have sex with tomboyish girls wearing male uniforms, as seen in the 02/05 CM.
The game will also feature 8 heroines with various body proportions and personalities. And one of those girls is the protagonist big sister, so... there may be incest.
Illusion said their game will focus on character personalities instead of customisation, which means you won't be able to create characters nor customise the existing ones. So, nope, you sadly won't be able to change the girls boobs sizes nor the guy height. At this point, we don't even know if we will be able to change their clothes and haircuts.
The story will progress through some kind of "drag and match" mini-game (whose exact mechanics are still unknown) in a similar fashion of what you can find in HuniePop.
They announced their game to feature new mechanics that allow to switch positions without the animation being interrupted and also showcased mouse-controlled H-scenes in the 02/05 CM. Expect the controls to be similar to those of titles like Schoolmate (or even Real Play), where you had to click and/or drag the characters to change position, initiate sex and grind the girl.
They claim the game will include 192 different sex animations. It's highly probable that they count each variation of the same position as a separate "motion" to come with such a high number.
The game will ship with a "Free-H Mode". But it's still unknown if we'll have to clear the story before being able to access it.
On the Amazon page, they also claim that the game will feature "a new 3D mosaic that makes the insertion and fellatio scenes look richer" (if I translate correctly).
The pre-order bonus for the DVD edition of the game is an additional 3P sex position.
An Android version of the game will be made available (downloadable via QR code) to all those who bought the "Package Edition" of the game, and it will includes the exact same content as the computer version with the exception of the sex scenes. So, you will be able to play the mini-game and read the story on the go, before coming back home to enjoy the H-scenes you unlocked. Save data will be synced through Illusion's servers though, which means you probably will need a proxy or VPN to use this feature. It also seems like an iPhone version is in the making and that a voiceless version should be made available for free at an ulterior date.

ILLUSIONより、カスタムを排してキャラクター性を重視したゲームが登場。
そして、“スマホアプリリンクシステム” というジャンル名の通り、本作は スマートフォンアプリ との連動が可能。
アプリを使えば、パズルをクリアしていくストーリーモードがプレー可能となるので、電車の中や旅行先など、好きな時に物語を読み進めることができるのだ。
もちろんエッチシーンもこだわりのクオリティー。 おねショタを心ゆくまで楽しもう！
※→の画像はパッケージ版特典の追加エッチシーンデータより。