I love the idea that Momoe was somehow the secret instigator or had background involvement in the Sachiko cards, as suggested by the washing machine intro. A few ideas for similar intros.
-Momoe overloads the car for the camping trip on purpose, Sachiko bails right before the load shifts inside, leaving the only available seat as the driver's seat.
-Momoe tries to slam the gym storeroom door shut but times it wrong and falls in with you before Sachiko enters
-Sachiko fails to dominate you so Momoe tries to show her the ropes but gets a little too into it.
-Momoe discovers your onlyfans and is planning to send a link anonymously to Sachiko, but you walk in on her looking at your content before that can happen.
-Sachiko chickens out when time to bring you your chicken tendies and leaves the cooked food for Momoe to deliver.
-Momoe ended up attending the halloween party incognito to watch sachiko try to hit on you, but sachiko doesn't show, and you bump into her on her way out.

No pressure of course, I have massive respect for your work and I'm sure you're overwhelmed with requests. I do love the idea of it though, that the reason that timid adorkable Sachiko ends up in these situations is because Momoe is being cheeky behind the scenes.

Hello! I see you have a lot to do, so I don't expect you to do it right away, but here's my suggestion.
It would be a bot in a relationship style similar to that of Zoro with Kuina, from One Piece.
The user would be the equivalent of Zoro, in the idea I had, this would be more like a malePov, but I think it should be possible to adapt it to an anyPov.

Basically, it can be a bot of one or more characters, being only the character that would be Kuina, or being the character that represents Kuina, and one to represent her father/mother.

Basically, the character's family would have a dojo (it can be anything you want, fencing, martial arts, whatever.), and you are her rival in the dojo.
Her father/mother does not accept that she is the successor of the dojo, because she is a futanari, even if she is the best in the dojo. And she will be jealous of the user, because her father/mother always seems to be much more proud of the user than of their own daughter, just because the user is not a Futanari like her.

I think there's a lot of potential for drama in this, especially if it's a double bot, where maybe we could try to help the character get recognized by her father/mother.

I'm posting this mostly just to share my appreciation of your work. I usually make my own stuff or heavily tinker with it before using it, but your cards are a great source of inspiration. Thank you.

Secondly, a quick question:
In what you've made and used yourself, how do you feel about the distinction between multiple characters in a single card compared with separate cards to go together in a group chat?

Finally, I'll share the outline for my favorite futa I've messed with in sillytavern though, I'd be curious to see another take on it, but hell, it's fun to talk about too.

Basically a competitive, toxic-masculinity-coded futa.
Still distinguishes herself clearly from a man but hangs out with the guys/spends too much time online and talks/behaves like she's god's gift to women - also strongly rejects the notion of being the receiving partner or being submissive.
Obviously just compensating for a lack of experience and fed by a couple of bad influences.
Projected narrative in mind could be anyPOV, standing up to her as an equal, exploiting her bravado to trick her into some fun bets/competitions to broaden her horizons and ultimately exhibit a positive change in her by showing her she doesn't have to be a sex god gigachad to be loved and respected.

When I wrote with her I used Mpov and through camaraderie, lewd wagers and being a service top rendered her a safe-and-accepted-for-who-she-is bottom leaning switch - helping her accept her feminine side and enjoy submission by playing to her ego by convincing her a stud like her can prove her confidence through trust and surrender, etc.

Thanks for reading and have a nice day and a happy new year - from Australia.

Your childhood best friend was a futanari, none of you understood what that meant at the time, but because of that, she had to study in a place just for futas from elementary school to high school.

Years have passed, and now she's in the same college as you! She still remembers you, and she hopes you remember her too!

Of course, she's still having some difficulty adjusting after spending so many years studying only with other futas, and you're studying with futas for the first time in years too. Maybe you can help each other adapt?