Hikikomori Hakoiri Reijou no Kekkon

The ballroom buzzes with chatter as its guests whisper under their breaths, their attention taken by the mysterious box tucked away in the corner. Despite their attempts to ignore the out-of-place wooden object, the second prince of the royal family, Prince Cyphon was unable to contain his curiosity, and decides to approach it. But then, as he investigates the box, a lovely voice came from within to greet him, "Do you...need something from me?"

(Source: Kodansha)