Kokoro no Kagi wo Mitsukete

Kazuto is injured and living alone when his half-brother, Kiyoto, sends their servant, Toudou, to assist him during his recovery. However, Kiyoto's true intentions are not centered on Kazuto's well-being but on something else Kazuto owns. As Toudou begins to develop emotions beyond his duty, the question arises: how faithful will he remain to his master when personal feelings come into play?