Wakasama Oshitai Shiteorimasu!

Even in today's society, ninjas are active in the dark. One of them, Kon, is a bodyguard for Yuichi, the next head of the Nikaido family. Kon loves his lord so much that he interferes in certain arranged marriage proceedings, leaving a sexually frustrated Yuichi meting out sexual punishment on Kon. While Kon's happy that his beloved lord feels his body, his heart aches at the thought of Yuichi's future happiness without him...

(Source: Frontier Works)