Enter with Rikako

"Why don't you join us?" you say.

"Me?" Rikako asks, clearly not expecting your words.

"Honestly I don't know them and don't know what to expect."

"But I've no experience in this kind of thing!" she protests.

"So do I. We're in the same boat together," you say to end the conversation while opening the door. The two of them are waiting for you, dressed in loose bathrobes. One of them smiled, dressed in pink bathrobe, flicking her neck-length brunette hair seductively. "I'm Shinobu" She then gestures to the other woman whose long hair is tied up in a bun. "and this is Hisae. Please come in. We've been waiting for you."

You enter with Rikako in tow.

"Hm... this is a surprise," Shinobu says. "I thought that we're having a threesome. Seems like I was wrong. So, foursome?"

You consider her question. You can have a threesome with Shinobu and Hisae, or foursome by involving Rikako as well. Or else, you can subvert everyone expectation by having sex with Rikako and only having them watch from the sideline; it's like some sort of a reverse wife-watching but involving the wife of someone else.