Toranoana Bonus Manga

The Toranoana Bonus Manga is a series of limited edition Monster Musume comics created by Okayado and distributed by the manga and anime merchandising franchise as part of a bonus for purchasing Monster Musume volumes at their stores.

Sofa of Slothfulness Conclusion (Volume 6)
Some time later, following the first two incidents involving the Sofa of Slothfulness, Lala also attempts to try out the new sofa only to meet a similar fate to Rachnera, who also attempts to lay in the sofa a second time only to once again be molested. As Rachnera and Lala lay recovering on the ground, Kimihito decides to try out the sofa despite Rachnera's attempted warnings, however, as Suu began attempting to molest him, Kimihito began instinctively molesting her; manipulating and playing with her breasts and nipples until she orgasmed and lost her ability to retain the form of the sofa; revealing herself and the loss of the Sofa of Slothfulness.

Where is Darling's Parents? (Volume 7)
The residents of the Kurusu household try to deduce where Kimihito's parents are.

Trivia

 * Melonbooks is another store chain that releases bonus merchandise with Monster Musume volumes. In this case they give away limited edition covers, drawn by Okayado.

http://www.crunchyroll.com/anime-news/2013/11/13/drunken-new-years-centaur-featured-with-monster-musume-release