The scenario is interesting but currently there is not enough content to see where the story goes. Just hope that the mc is not railroaded to become gay. When in the female body, the mc should be able to hit on girls leading to lesbian scenes. This tag is currently missing. I don't mind crossdressing or body swap in games as long as the mc is not forced/railroaded to have sex with males.
A lot depends on how the body swap turns out :
- permanent (they continue their life in each other's body and have to live with the swap)
- recurring (swap and swap back from time to time or in special situations, eg when fighting each)
- limited number of (later controlled) swaps and back
Edit :
I mistook the "You get to play as the sister part of the time." as recurring body swaps, so the following comment might seem a bit out-of-place.
I remember a game with a similar story :
https://f95zone.to/threads/tasty-curse-v2-55-favoritecat.117931/ . It's been awhile since I played this.
There by accident the male mc repeatedly switches body with his female roommate for a day. If mc makes her really angry, one day while bodies are swapped, she may rape mc by fucking him in the ass to teach him a lesson. (It's actually her body, so she knows she/he can take it in the ass, but it is him to suffer the pain for the day and to remember.)
Repeated body swaps for a limited time have a great potential to corrupt the other persons body (eg by working out, not working out), friendships (hang out, flirt, have sex with friends or piss them off), clothing (buy new stuff, throw other stuff away), ... If mc is a perv, he might even shave his sister's pubs while in her body (or vice versa) to give her/him a surprise when they switch back (Note : here the sister has "a neat little pussy, shaved clean") ... a lot of potential but also a lot of work to implement that all, because the next day the sibling has to deal with all the changes and the friends may have to deal with repeated schizo behaviour of both until they share their secret.