We would know after this sequence

Issei wakes up from his dream slumber and conversation with Voice-san, now back to his room. The morning had come by and its time for school. Looking beside him he sees Asia and Mittelt sleeping in their nightwear(replaced from the previous one). He had made a rule for these two to sleep near him. Issei grin as he rubs their heads.

Hehe, He feels closer and closer to become a Harem King.

It does feel a bit cramped here, Issei thought, maybe he should buy a bigger bed? A Harem King would need a bigger place to sleep with his girls. Of course, he won't just try to own it, even he has some standard, however low it is now.

Issei goes back on what Voice said, on the foresight, he better be prepared for it.

Although, what does he exactly mean on the first one?

And why does his dick feel cold? He looks at the sheet to see it being a bit damp, did he pee himself? Or was it the girls? Like he may now have a fetish for seeing them doing the deed before, but at the bed is a bit much since they have to clean that.

Actually, he notices a massive bump on his sheet, and there his mind goes into overdrive. This would be a situation where there is a girl infiltrating a guy's bed to have some fun time.

Who would be getting inside this room? It couldn't be an unwanted trespasser. He had already placed a rule to prevent any from even getting close to his home.

So, Issei yanks it off to see who it is. And there he realizes why his dick feels cold and wet.

Looking, he saw a female humanoid sucking his dick, the girl(?) in question look is all green and smooth, the same color and texture as Slime-Taro, his shorts are removed and on the floor as the girl made a slurping sound. It felt nice.

Actually, where's Slime-Taro? Issei look at the makeshift home he had made for him which consist of a big acid-resistant plastic container, and he saw no big lump of green slime.

This is an odd time for Asia to woke up, as she noticed the slime girl and has a confused expression.

"Ehh? Why is there another girl licking Issei-san's-" Asia's face became red as she can't finish those sentences.

He looks back at this slime girl who is still continuing sucking his dick, remembering his conversation with Voice, he made one probable conclusion.

Slime-Taro had become Slime-Chan.

"Good Morning, Master?" Slime-Taro reveals another massive revelation by just speaking.

"Eeeeeehhhhhhhhhh!!!!!"