The story is great, the plot phenomenal. This manga has an enormous potential if the Mangaka put work onto it. For what i reckon, the protag may have some sort o trauma because of his younger sister, that perhaps is what makes him "indifferent" at mitsukura body.
Honestly? If you gonna make this, at least have the common sense to use the other 2 girls to indulge in some Yuri ecchi fanservice. Yeah, the main bitch is great, but more than 30 pages of only getting her in langeries and sportswear ain't it.
The manga is bland, has all the sauce but it's like the dev doesn't have his cock hard enough to start writing something. We got some hints as mitsukura masturbation scene, but that doesn't make it clear if he is gonna grow a pair of balls or not
The MC is traumatized? We got a sapphic bitch right there on the manga club, use her to give something else than just retarded photoshoots. At least show us her lewd depictions of Mitsukura, and not just put them making some ridiculous faces looking at it. I already got from the 10 initial chapters that the MC is gonna be the usual bastard that it's only useful to irritate the viewer with him being a no-dick.
Despite that, great art, great plot. Add more Ecchi, hug it without being scared that you may propel it even further.
Add a lot more Yuri, being more suggestive and putting Ecchi into it and it will skyrocket it.