Joining Miki from Viper CTR and Raika from Viper F40 is Natsumi Aihara from the eroge X-change and X-change 3. While Miki and Raika are here because now there are pics of them having sex with just one guy and actually enjoying it, Natsumi is in because now there will be images of her having sex PERIOD. Not even kidding, in both games, she has one scene where she sits on someone's face and one where she breaks out a black strap-on to use on a girl. And the very first panel of this comic shows more of her body than EITHER of those did.
TLDR: She's yet another reason why I say Japanese game designers wouldn't know what to do with an actual hot, fuckable woman if one tripped and landed on their cocks.
For those who give a shit about plot, I'll sum up the original comic I rough-drafted for this once upon a time. Miki and Raika are roommates with a mutual fuck-buddy/boytoy, who Miki invites over for a surprise threesome. Natsumi is a bitch who pretends to be completely gay rather than admit she's bi, but sometimes her hormones go "WE NEED A DICKING!" and she finds a guy to have sex with. However, her attempts to remain in control of the situation don't work and she eventually lets the guy fuck her brains out, and she loves every second of it.
Or to put it another way, it's a drawn out version of the "Instant Loss" meme, and I feel VERY strange that I came up with this scenario before that meme even existed, and yet the description fits perfectly.
Of course! I’m not abandoning that one by any stretch, I just had this idea jump into my head and needed to get it out. If anything, consider this a ‘coming attractions’ for my plan after A Sister’s Advice is done.