>>151149366
wouldn't it be better to have a male character that just cross dresses for the fun of it? Plenty of American cartoons like following into anime tropes, so why not do the trap/otokonoko thing.
but if we must have a situation.....
Say a family with a teen girl who only has brothers and a dad. Her mother and father divorced and he isnt into getting remarried just yet, so she complains how the whole house has become a sausage fest because she's the only girl in the house and has no older sister or female figure to look up to. Her eldest brother who wants to get closer to her overhears her qualms about this, so he decides to crossdress and become her "big sister" as a stand in. She finds it odd that this is his plan and doesn't see how it would work because hes a man and would maybe only understand girl stuff on a surface level. She eventually goes along with it and starts calling him "brosis" as a nickname.
While an odd plan, it somehow works and brings the siblings much closer together + the brother has a new found appreciation for woman and girls and what they go through on a daily basis since he's started crossdressing. later on he discovers he actually enjoys dressing that way and drops the "big sis" act.
If anyone else would like to add onto or improve the story, be my guest