In the Mr. Secret Floor series:

V.1 - Shousetsuka no Tawamure na Hibiki (Reverberation of the Novelist's Game)
In the super luxurious hotel Grand Ocean Ship Tokyo, there’s a special floor exclusive for royalty, tycoons, politicians, and Hollywood stars. To keep their anonymity, they are referred to as “Mr. Secret Floor” by the staff.

Yamagi Kyo, bestselling novelist, is a permanent resident in one of the rooms in this secret floor. In fact, he’s the half brother of the owner, Shirahase Taka, from a different mother. As a famous mystery writer, he’s sought after by many publishers. Aiba Takuto from Cosmo Publisher was newly appointed to handle the task of obtaining the famous novelist's manuscripts. How far would this new editor go to get the manuscripts?

V.2 - Honoo no Ouji (Prince of Flame)

V.3 - Sabaku no Kaori no Otoko

V.4 - Gunpuku no Koibito

V.5 - Boku o Kurau Kemono no Kagayaki

V.6 - Bokura no Special Baby