Molester’s Train: Mischievous Fingers (1982)

Molester’s Train: Mischievous Fingers | 痴漢電車　いたずらな指 | Two men get to know each other through their shared love of groping on the train, and fall into a bromance. They build a set that looks exactly like the train, and when they open a shop where people can come and play groper with their models inside of this set, it becomes very successful.