How will I find or get it?
Nipple Vore, Breast Expansion, Monster, Futanari · By
in World 1, after saving the angel from the sealed gate, head to Lust Realm.
The green hair girl will let you get in the Futa Valley, you complete the quests inside the valley then you will get a Diamond Pass.
Take the Diamond Pass to succubus night club, head to the VIP/Boss room, complete the boss quest then you will get the experimental dildo.