This game is about a schoolgirl with a bag of holding and a rubber fishing line setting out to rid the world of giant mutant fish.
Actually, it's more like a little-known Japanese wire-action platformer (like Bionic Commando or Ninja Five-O) with a small but rabid fan following. Like Ikaruga, the game is very easy to win, but very difficult to play. This video demonstrates one of the fastest paths to the ending, including quite a few almost impossible maneuvers - whether playing tool-assisted or not.
This video is a 2 seconds improvement to the previous version, due to competition between blechy and Bob_Whoops.
See the Umihara Kawase page for more information about this game.
Ps: If the SMV desyncs for you, first ensure you have the correct ROM and that you don't have sound disabled. If it still desyncs, ensure that you don't load the movie as soon as the emulator has started: give it a few seconds first.
Bisqwit: For extra fun, get your hands on this game and try playing it. You'll quickly learn what "almost impossible maneuvers" means :)