I have to admit that I barely made it through the first episode, so if 'Kandagawa Jet Girls' surprisingly manages to get any better from episode two onwards, please disregard this review.
In 'Kandagawa Jet Girls', a popular sport is is to ride a jetski down a river and fire waterguns at opponents. If an opponent is hit, they typically seem to lose an article of clothing for some reason. Nevertheless, this is seen as a fairly respectable sport.
School girl Rin freshly transfers to Tokyo and wants to become a professional jetski pilot. She teams up with her friend Misa, who shoots the watergun of their jetski. In the first episode, they are challenged by an opposing team, and I assume that each consequent episode will feature a similar challenge until they win some sort of championship (which Rin fawns over).
This premise could be reasonably fun, but the characters are generic to the point of being irritating. The fanservice is far too plentiful, featuring heaving bosoms in an otherwise touching childhood flashback and bare breasts not soon after.
In total, I'm just not sure what 'Kandagawa Jet Girls' is trying to accomplish. For a genuine show about a quirky sport, it is too bland and oversexualised. For adult entertainment I'm sure that any genuine adult entertainment would be far superior. The only apparent selling point is that all the characters and their relationships are female, which could include romance if you squint really hard. If so... ugh, c'mon, really?
From a technical standpoint everything seems up to par, so I'd give it a 4/10.