Training Gin

Meeting Gin
To meet Gin, you must defeat any Wildcat through lust damage first. He would freak out, and call that "unfair", because he can't defend against such attacks.

Lust Doll would offer to train him, starting the quest and making Gin available for interactions. He would spawn on the Forest Park's entrance.

Training
At first, only three options are available: use your boobs, butt or feet, which leading to the different sex scenes. Gin can't be trained more than once per day, so some rest is required before training can be continued.

After repeating the training enough times, the options to go further would unlock. However, Gin would freak out at the last moment and run away.

The next day, he can be encountered on the same spot as usually, and you can try to push a bit further again, but his usual shyness would ruin everything at the last moment yet again. As of r20.1, this is as far as you can go.