比翼は愛薊の彼方へ ～未了の因～

The story is based on "Sangokushi" world. Shoukou is appointed to the successor to the country. But some people don't agree with it, and Shishi plans to assassinate him. Kakukai finds it, and Shoukou and Kakukai run away from the country. They are run after by Shishi and his group. As they run away together, their relationship becomes closer, without knowing Shishi's intention and a neighboring country's conspiracy.

[Edited from Erogeshop]