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.