she's a cabaret girl (hostess, not a sex worker) and that guy's favorite, and hoshimi herself tried to get close to him and his lackeys after she found out the possibility of her sis being kept in captivity by that guy in his building. There's 1 room where nobody can enter but him, but it needs a keycard and pin number. It ends up with hoshimi seducing his lackey.
Later on she seduced him into a hotel, the plan is for hoshimi to contact that guy and tell that his lackey touched her, his favorite, while sawaya is an insurance outside the door ready to break in, It failed and sawaya broke the door. The lackey just said something kinda like "do you want to save your sister or what? then the answer for what you should do should be clear". then hoshimi just went "i promise you, you can do what you want to me after my sis is saved" and starts to give head to him while announcing to sawaya this is what it entails being with her, she won't stop at anything to save her sis.
Sigh, he should've just forget hoshimi and be with his (not rly there) gf, or just hook up with miwako, she likes him way too much.