My Noisy Roommate: The Roof Over My Head Comes With Monsters and a Hottie, Vol. 3

After Nijio's ex-partner tried and failed to come between them, and after so many successful cases together, Nijio and Osuke's relationship has deepened. But right as they finally begin to trust each other as partners, Osuke's older brother and sister come knocking at Divine Inspiration! Osuke's overprotective siblings are raring to take their precious little brother back home where he'll be safe and sound. But Nijio might have something to say about that. And just why do Osuke's older siblings recognize Nijio? And what does this have to do with Osuke's powers?