Kamen Kotei Ikai no Choki (Kadokawa Ruby Bunko)

[Machine Translation] In order to pay off his father's debt, Sai chooses a job that pays well, but it involves flying to another world and proving its existence. Unable to turn his back on his father, Sai flies to another world and is suddenly almost captured by the military police as a smuggler in the Chinese-style world he arrives in. However, he is intervened by the masked emperor, Ri-oh, who rules the country. He allows Sai, who possesses a "dragon mark" that brings prosperity to the country, into his palace and shelters her as his mistress. Sai, who is loved like a real queen, gradually opens his heart to Ri-oh, but when he finds out that Ri-oh has a secret...?

父親の借金返済のため斎が選んだのは、異世界へ飛んでその存在を証明するという眉唾ものの高報酬バイト。背に腹は替えられず異世界へと飛んだ斎は、到着した中華風の世界で、突然密入国者として憲兵に捕らえられそうになる。ところがそれを制したのは、この国を統べる仮面の皇帝・璃王だった。彼は国に繁栄をもたらす「龍痕」を持つ斎を後宮に通し、愛人として匿ってくれる。本物の寵妃のように愛でられ、斎は次第に璃王に心を開くが、璃王になにか秘密があることを知り...!?