Hiiragi-Senpai To Ofutari-Sama summary:

After repeatedly changing schools due to her father's job transfers, Moemi decides to stay at her parents' home on the condition that she lives together with the daughter of her dad's boss. However, the girl she was told to live with is in fact... a boy! A senpai from the same high school, Hiiragi! Suddenly living together with an older boy starts off with a lot of excitement...?!