Eikoku Monogatari Shunka torikae Shou
榮国物語 春華とりかえ抄
The twins Shunran and Shunrai are frequently misidentified as the opposite gender. Shunran, the elder, is intelligent and wishes to take the civil service exam rather than join the inner palace. Shunrai, the younger, is noted for his appearance and is expected to enter the palace. To achieve their goals, the twins decide to switch places, with Shunran taking the exam and Shunrai assuming his sister's role in the palace.