I've played a number of releases from September's releases, and I'm currently playing Renai Phase (which I'd promised not to, as Giga is incapable of making anything truly great outside of Baldr). However, this month really doesn't have anything I'd really consider VN of the Month material... Seikishi had its fingertips on the vague possibility, and it is undeniably the best thing I played from September. Unfortunately, 'the best from September' is not good enough.
The reason I'm already putting a 'batsu' mark on Renai Phase, even though I'm only halfway through it... is because the 'koukan do' system intrudes into the VN in a manner that breaks the storytelling completely. Whereas in most VNs, you have to guess which choices do what with how the heroines feel about you, this VN commits the sin of making a noise and showing a little visual effect every time... and it is really intrusive. I know this might sound like nitpicking, but the sheer number of choices in this VN means that this is hair-pulling level annoying. Not only that, but the protagonist in this VN is fully nameable, without the brilliant system Hoshi ori used that allowed it to have redeeming value. Last of all, the greatest sin of this VN is that, from the very beginning, the protagonist is setting out to get a girlfriend on a whim. To be honest, VNs that steal from dating sims piss me off in general, but this one is particularly offensive, in my eyes. Unless the heroine paths are superlative, in my opinion, this VN has already axed any hope of being VN of the Month material.