Yuki no Oshikko Omorashi Jijou -Yuuenchi Date to Rinyouzai to...-

After hearing Yuki tell a story of how she once wet herself on a bus,
the protagonist longs to see her like that.
During a dark at an amusement park, Yuki is given a diuretic,
and wets herself on all sorts of attractions.

[From DLsite English]