New ideas at 14/9:
1. Does the "kikkoushibari" hear that before? I think it is good things for tentacle. Even there's a lots of another style of "knot".
2. I know I've mentioned this before, but I have some details to add about cumming scenes. The tentacle can got wet when the girl nearing cum, not only after cummed. So, may be "liquid dropping" can be consider add into the scenes. The surroundings can also change with the number of times of the locker used.
3. Similar to the second point above, the tentacle can covered with liquid after "serviced" someone.