My Older 'Sister' Can't Be This Cute!

What turned out to be a normal experiment would turn out to be the former CEO of 'Tokosomi Industries' worst nightmare, his gender and appearance now taking on the look of a young highschool girl. When he learns that this effect is permanent, he has now has to adapt to being a female version of himself, and attend highschool again with the help of his younger brother, nephews, and nieces.