Based on the CG collection by Churu Bitch Churu Churu (ちゅるびっちちゅるちゅる).

On a sunny holiday he took a drive to a certain rural village and awaiting him in an open-air bath were, unexpectedly, three little loli girls all in naughty outfits.

The three introduce themselves, and the service begins...

(Source: DLsite English, edited)